Unlike you, I do not believe that "everyone" knows instinctively that homosexuality is a perversion.
I happen to have know quite a few heterosexuals that are exceptionally perverted. And I can say, without a doubt, that they were not performing these acts for procreation.
However, I do know that some people feel very strongly about homosexuality and everyone is entitled to their beliefs. But it is NOT OK to discriminate against this group of people, in fact it's against the law, as it should be.