Every organization makes rules.  The Church is no different except that it is not just an organization; it is a body created by Jesus. The Church is not requiring that someone "deny his sexual orientation" or pretend he is someone he really isn't. The Church is saying that someone who has homosexual desires or acts out his homosexual desires may NOT be a priest. There is nothing wrong with making rules like that. Just because someone wants to be a priest doesn't mean he is qualified for it. If he doesn't meet the requirements, he should not be admitted to the seminary. If this rule had been followed 40 or 50 years ago, we would not have had the problem of sexual abuse that we have had. The sexual abuse scandal was caused primarily by homosexual priests.