I think it would have been wise to avoid the interview altogether as Phantom255x suggests, but this is not always a choice you can make.
Given the awkwardness of the situation, he managed well and kept his cool throughout; it could have easily been much worse.
He came off as an opinionated and stubborn guy. I love that.
PS He sure has a big ego, and this would have been a major red flag if he were not talented. But the talent is there, and the big ego-big talent combo can work out pretty well.