(or any other major transgression or issue that BYU BOT would care about but other schools would barely notice). The coach would be immediately dismissed and then we have no head coach, upset players and parents, and a quick fall from our position as the school with standards.
I'm not saying non-Mormon coaches would get a DUI, or that a Mormon coach would never get a DUI, but BYU is playing the odds that a Mormon coach is not likely to get a DUI.