I saw quick clips of it this morning on Sportscenter, but yeah, I can see what you mean by it seeming phony and fake. He has to be at least a tiny bit upset though --- he took his suspension, his $75K fine and his anger management course in hopes that this could all be swept under a rug... but now he gets fired anyway in a very public, very shameful way that ensures that he will not be back in coaching a long time.
Seeing his sideline demeanor with players and refs, is it possible that all coaches are that way with players behind closed doors? We've seen our own football coaches go crazy at players during games on the sidelines. While it's not the same (because there's a lot more protection for a football player in shoulderpads and a helmet than a basketball player in nothing but shorts and t-shirt), I hope that sideline demeanor isn't a big red flag that something worse is going on behind closed doors.