Pecos, I get that religion brings out the crazies, just like politics. And all religions have things about them that look weird to others. That's why a premise of religion is faith…faith in what you believe. And thank God that we live in a country where you can believe in what you want. Normally I don't care about posters degrading my faith, but if it's false, I'll correct.
Polygamy was a history of the Mormon faith, it hasn't since the 1890s. I don't see a single similarity in Koresh's Branch Davidians and the Mormon faith. No doomsday prophesies, apocalyptic prepping, or commune isolation. But it's your God-given agency and first amendment right to say so if you believe so.
I tend to follow coaches when they leave BYU. Grimes was a special one who made significant improvements to BYUs program during both times at BYU. Having heard him and his wife at pregame events speak about their experiences at BYU, I doubt they would agree with your assessments of members of the Mormon faith either.
As a BYU fan, I'm very much excited to see new opportunities in the B12, a fit that I believe is better than what the P12 could offer or what Independence was providing. I hope you take the opportunity to visit Provo for a game, take a pregame tour of the stadium booth offered only to visitors of opposing teams, see the conference-mate flags flying in the endzones, the free ice cream during the game that's offered to those visitors, sing your fight song played by our band. Hopefully the teams take the opportunity to pray together at the conclusion of the game like after BYU played BSU or sing fight songs together like after BYU played Navy last year. After all, after the game ends, we all have more common than just fans of opposing teams.