Trent Reznor looks like a Ti user but I will look closer later, I don't have a lot of time right now and I could be wrong.

It’s turned out that most actual Pe-leads are artisans of some sort — musicians, painters, singers, athletes, etc — and Pi-leads (proper) are more often academics, counselors and professionals (i.e. doctors, teachers, psychologists). I would say that Pe’s have “a talent for the dynamic” while Pi’s have “a talent for the scholastic.” From the behavioral dimension, I’ve found this can be rather informative in conjunction with vultology. Trent certainly fits more into the former than the latter.

I can not disagree because you were talking only about most Pe-leads, implying that there are exceptions, but what I wanted to add is that many people (including Pe leads) lack artistic skills and that Pe-leads' talent for the dynamic might also help in most jobs that involve working with/for other people. Including counseling, which also has the advantage of involving adaptability and openness to different possibilities, which are qualities many Pe leads have.
Oh, George Martin is NiFe, so, we were wrong about his J-axis, interesting. Now I actually think it would make more sense for him to be an Fe user, the books are about a game of thrones in the end. The main themes are political and social and character's motives are very well explored. It is not so much about an individual doing what is aligned with his own inner values but more about families and houses fighting together and against each other. There are also a lot of practical life lessons to learn.
I must learn to differentiate Fe and Te movements better.

It's really quite hard to determine because everyone always has one agenda or another. And I mean it in real life too. Someone mentioned it in the chat today quoting someone else (I don't remember who) and I agree, of course. Everyone has an agenda. In politics you must adopt an ideology or another. It can be - A Lannister always pays his debts or Winter is coming but they are at their roots ideologies, though we agree with the second and roll our eyes at the first. :)) I mean, of course, very simplified ones, but there is a belief system at the root of these words. And it is shared by all members of the house. It can be adopted by others too when one ideology becomes more in line with the historical reality (during summer and when people did not know about the dangers behind the wall, No Debt might have been more compelling 🙂 like...in our case right now it makes sense to fight for the environment but 100 years ago we considered other values more important ).
About characters who are portrayed as good guys vs. bad guys, this is very complicated because there are a LOT of characters, I believe all types must be covered and almost no character is completely good or evil. Which I actually like, but at some point it becomes hard to determine who you should be rooting for. 🙂
Dany started being seen as a "bad guy" recently (I considered her to be going downwards from the moment she burned the Tarlys, I was totally on her side until then and closed an eye to everything stupid she did until that point, because she had a fantastic development !).
I doubt Te-Fi characters are necessarily depicted as good. I don't remember what type Cersei is but I think she must be a Te-Fi user... at least in the show. Sansa is Fi lead and just started to be likable one or 2 seasons ago.
Jon is one of the few good characters and he is SiFe, I think. Auburn told us and I think this is his type. Maybe you can remember something questionable he did, I can't right now, but I might just omit it. To me he is simply good, with no dark or gray areas.
Ned Stark was also a good guy. I don't know his type.
I don't think this means much concerning George Martin's typing, all I wanted to point out is there are good, evil and neutral characters of different types.

The difference is that Se people see “reality’ as lived experience in the concrete world while Alphas may view it as something like ‘statistics’ and ‘possibilities/probabilities’ – which may lead to alpha vs. gamma arguments.

You are right ! But reality is just reality and it must be somewhere in the middle. If I know my personal experience is different from certain statistics, there are some possibilities - I can be an exception, the statistics may be wrong, the statistics may be right but apply to a different group, I could have misunderstood the statistics etc. It must be determined what is actually true.
But there is also a question regarding how to address this, which is another issue that I don't fully understand yet and am still experimenting with, but I am diverging way too much from the topic. 🙂

I've looked at a few more interviews, and found this one particularly insightful (youtube.com/watch?v=MdSPFJcxCNM) as it describes his progress as an author through time.
He wasn't just born writing this way, but had to work hard at it and learn a lot of lessons along the way. His writing style is something he cultivated over time, including his character-focus narratives. Reading his earliest works before ASOIAF may also better illuminate on his psychology.
(But there's also the obvious which is -- not all Gammas are international bestsellers. In fact, being Gamma or Beta is irrelevant to the production of compelling works. I'm sure there are poor NiTe writers who can't convey subjective character experience well, and NiFe's who do. So I don't think we should attribute his success too much to any function, per se. That's what causes mistakes like people viewing Einstein as INTP because "how could he not be, look at his works?!")
 
Early Writings...
But insofar as we might take a fair approach at his work and what it conveys, I'd prefer to start at the beginning -- before his talents emerged to balance out any imbalances that a writer might have had due to their cognitive starting place.
His first publication ever was a story called The Hero in 1971 (link, page 119). It's about a decorated war-hero Kagen who is a space fighter and has earned many honors in his 20+ years of service and now wants retirement on Earth, which he's never actually seen before (humans inhabit other planets now too) but which his time at war should earn him a place in and which represents the planet he's been fighting to defend for decades. The Major, Grady, resists his desire to retire and doesn't wanna let him go -- saying that although a solider's "benefits" do guarantee a bountiful retirement, almost nobody actually retires. After insisting, the Major agrees and puts him on a spaceship to earth and to his retirement, ...only to actually kill him on the way there.
An interesting detail was that as he was being killed, his war medal (a "Stellar Cross", was pressed into his chest making him bleed). So there's some Christian symbolism there too.
I see this story as a commentary on political corruption. Does the Major never actually pay-out his soliders? How many others who have tried to "retire" have gotten killed? What cause are they actually fighting for? Is it all a fraud/scam? What is Earth actually like?
The message seems to be "even if you fight heroically for your cause and are a good citizen, political/financial corruption will make your efforts vain" as well as "your cause is a lie."
This short-story does seem Fe to me, but more specifically a kind of angsty and disenchanted Fe. It's an Fe story that is tragic and unfair, but it's clearly a commentary on heroism (Fe myth) too.
This still says nothing definitive about George R.R. Martin himself, but at least I'm starting to understand his mind a little more. It's conceivable to me that his approach in GOT is a result of a kind of a tragic Ni/Se realism and awareness that is destructive to Fe's aspirations and hopes. The GOT series always felt to me like throwing up the middle-finger to Fe's desires. We have Fe protagonists like Ned Stark who are honorable/noble, and what does the world play them with? Death.
And so the brutality & arbitariness of life ..the harsh meritocratic undertones of GOT... may not be a result of a Te writer writing about their Te, but of an Fe writer writing about their contentious (demonic?) relationship to Te's truths?
Something I haven't thought too much about until now, but which might be of value, is the notion of opposite-function myths clashing. We have Fe-vs-Ti manifested in "Void & Flame" and Fi-vs-Te in "Nature & Machinery" ...but what about Fe-vs-Te? Would it be something like "Reign by Honor vs Reign by Power"?
And could GOT be (ideologically) interpreted as a commentary on different methods of Je rulership?
I have no idea.

So he is NiFe after all !
(I am basically confirming the Se addiction theory by coming back on the forum 2 days after saying I'll take a break because I am falling behind at work :)) )
Regarding the methods of rulership - I think this is actually the main theme of the books ! The books and the TV show both seem to explore what makes the best leader and how different leadership styles fail or succeed. There are also some important issues about spirituality and how different religions fail or succeed but they are not the main focus.

The GOT series always felt to me like throwing up the middle-finger to Fe’s desires. We have Fe protagonists like Ned Stark who are honorable/noble, and what does the world play them with? Death.

I will disagree with this, but maybe it was not that clear in the show what GRRM wanted to point out with Ned's death. I can't remember very well what I got from the books and what from the show.
In my opinion Ned died because of his lack of diplomacy/political foresight and this is actually a lesson for the reader/viewer- that it is not enough to be honorable to be a good leader. You also need to be able to prevent horrible things from happening to you and to your people. You must also be able to read your opponent's motives and to prevent him from killing you. Because it is crucial for you to survive in order to be able to protect everyone that depends on you.
This is basically what Cersei told him and what puffs quoted above - In the game of thrones you win or you die.  He died because he lacked other qualities, not because he was honorable ! At least this is my opinion, I can't know exactly what George Martin had in mind.
Many of the Starks made some typical...Stark mistakes 😛 at some point or another - they trusted the wrong people, took hasty decisions, assumed the best instead of being reserved, chose to invest in other people instead of sticking to their own family etc. There is a process of learning for the ones who survived. They basically learn how to overcome their own flaws or what is needed to survive in the real world, remaining honorable.
I think Sansa, Arya and Bran managed to learn to combine their native inclination towards honor with appropriate survival skills. It's interesting that the combinations are all different from each other. But still honor is maintained and mixed up with something else, something that makes them stronger (hey, I hope they are still alive, I didn't see the last episode yet :)) ). At the same time, there are some identity questions- is this ..other thing a part of them or something completely foreign? Are they actually still themselves and still true Starks? Sansa learned a lot from Cersei and Baelish; Arya tried to become No One, Bran claims he is no longer himself.
I don't know if this is relevant regarding the Fe vs Te views and I think I will analyze them later or tomorrow because I am not sure you are right but I also don't have another idea right now.
But what I want to say is that the Stark story lines suggest that honor is not enough and that something must be added to it in order to survive and to become successful.
Maybe their stories are about Je that needs Pi support.
Tywin had an interesting talk with Tommen about what makes a good king (except for the part where he is manipulating him to listen to counselors and to get married :)) :
https://www.youtube.com/watch?v=doY0IjisBlk
A king must be wise ! I think many situations in the books are life lessons about wisdom and perspective. This is one of the reasons I actually can see George Martin as being NiFe from a psychological point of view too - since Fe is connected to mentorship and coaching and ASOIAF is very instructive ! There is a moral lesson in almost everything that happens in the books; we are not just being told a story, we are being taught how to act in the real world.. in the disguise of narrative.
To end this long post, ASOIAF is in my opinion not so much about people finding their inner essence and other Fi or Te themes, it's more about tribalism, mentorship & the human condition, as well as about balancing heroism with wisdom. But all these themes are general and it is hard to see his psychology reflected in the books because the narrative is very complex and it's hard to say who he resonates most with from his characters. (though I think it could be pretty safe to assume that it's Jon). 🙂

@Animal, I just saw you also said something above. I will return tomorrow because right now I can't stay longer. 🙂
Oh, about corruption and your cause being a lie...you can put it like this but I would put it in another way. It's more - this is the real world and this is what you could do or not do to be successful in it. It's very similar to fairy tales like Little Red Riding Hood ! There are big bad wolves. This is what happens if you get too close to them. I see it as realistic and instructive, but not demoralizing/making you feel like there is no more reason to fight because anyway you can't win. No, you can win and GRRM is showing you how. 🙂

^^Seconding this XD. What's funny is that I had that exact same observation of Ned Stark that Bera did when my best friend (TiNe I'm fairly certain) said that Ned Stark did nothing wrong; from an honorific/ moral perspective that is true, but he did do something wrong in that he didn't understand what kind of a jungle he was living in, to borrow a phrase from Solzhenitsyn. And that failure to recognize reality had terrible consequences for his immediate family. I do wonder whether P-leads identify a lot with realism and "how things are", and that polarized ones would be concerned both with "how things are" and "how things develop" whereas the opposite would be true for J-leads and polarized J-leads, they would be more focused on the ideal of how things should be and how to get them there. Just speculating 🙂
Edit: Hmm. I am almost positive that Frank Herbert (author of Dune) is an Fe-dom (FeNi I think), and I very much get the sense from his books that he is actively trying to teach important lessons to humanity through his fiction, but I failed to pick up on the same trend in GoT (granted I binge-read the entire series in the span of a couple days), instead finding the series as more of a very well-wrought page-turner than a treatise on morality. Whereas Bera, and my best friend as well, were able to notice that he had created a sort of moral system to impart lessons that you had to glean from the history and current happenings within the universe rather than through the more direct moralizing style of a Je-dom. (And iirc my friend picked this up from interviews of GRRM and from watching the show, with no direct knowledge of the books).

There is a moral lesson in almost everything that happens in the books; we are not just being told a story, we are being taught how to act in the real world.. in the disguise of narrative.