You can have a sense of how it would be to work with him in this interview with Lex Fridman[1]. I'm also curious how it would be to work with him since it sounds like he is full of himself[3]. But he I believe he has the right for it since all what he has achieved[3].
The guy also read couple books a week[4] for last decades
I watched that interview half a year ago, and came away with the impression of a curious humble guy who was interested in digging deep below the surface and working on big advances.
I think you meant to refer to [2], and that part of the interview is Lex Fridman interjecting him when he was trying to make a deep point about how to think about things.
[1] https://www.youtube.com/watch?v=Nb2tebYAaOA
[2] https://www.youtube.com/watch?v=Nb2tebYAaOA&t=3973s
[3] https://en.wikipedia.org/wiki/Jim_Keller_(engineer)
[4] https://www.youtube.com/watch?v=Nb2tebYAaOA&t=5040s