I am very quiet about my fandom, but just when people find out that I just graduated from BYU, I was treated with incredible disrespect at church in Logan. Salt Lake is actually more reasonable, but a few of the most faithful members in my ward (EQP) happen to be some of the most rude when it comes to BYU. If it were just cutesy little jawing, I'm fine. When you start to tell me that my alma mater shouldn't exist, that it shouldn't play sports, and that I'm self righteous, I'm entitled to get a little defensive.
FWIW, I think the OP overstated things a lot. On the other hand, I do get frustrated when people who I consider friends have absolutely nothing nice to say about my alma mater, and the flagship institution of their church.