Yeah, it sounds like the guy has a bias and it muddles and inhibits his thinking. I think we've all known sports fans like that. I once had a German national who was a Schalke soccor fan insult me at work because I liked Bayern. I know and care very little about German soccer but this guy was nuts for Schalke.

As I mentioned I ended a 30 year long friendship with a good friend because he went nutso in hating a particular politican. He demeaned and insulted a number of us who liked that politician. He would not stop. Even his wife told him he had gone off the tracks. People get mentally fixated and are unwilling to take well intentioned advice.