Please don't pretend that bad behavior from fans or players doesn't happen at BYU. My buddy got spit on back in the 90s when we were leaving a game at then Cougar Stadium where BYU had beaten us handily. We were saying anything (we wouldn't have any way, but particularly because we had just been beat) just wearing Utah gear. Ironically he was beginning to take the discussions at the time, but that pretty much cured his interest.
I don't know that he would have ever joined, but it sure didn't help, he still talks about the hypocrisy.