I generally am not a fan of the excessive taunting after a knockout, but Askren deserves it with how he runs his mouth. As I said during the fight upthread, "Talk shit, get hit."
If you are humble in the run up and get embarrassed, you aren't generally going to have people doing that. Look at Masvidal after he bludgeoned Till. They had a more traditional type of run-up with more friendly banter shit talk, and Jorge was magnanimous in victory. He had some nice things to say about the young man, saying Till was young and would be back, etc...
People hating on Masvidal for the celebration can't want it both ways. As we learned from McGregor and Khabib, it is the guy listening who gets to decide how real the shit talk is and how personal to take it.