there's a difference between being a Catholic/Baptist/Atheist and attending BYU and being a Mormon who converts to Catholicism/Baptist/Atheist.

You all are misunderstanding my arguments. I'm not advocating for the rule, and I don't necessarily even believe it's a good rule. I'm not saying I'm in favor of BYU's rule, and I don't feel threatened if my daughter's roommate left the Church. I'm merely showing that there is a counter argument in favor of the rule.