Sure, they are all scourge of the earth. However, they are still human, albeit morally reprehensible humans.
They should face the consequences of their crimes, but yet as civilized people we still have the moral duty to allow them with certain human rights.
However, the problem with the analogy (aside from being offensive and inflammatory) is that unlike gays, their rights have nothing to do with the reason we condemn them.
Nazis have the right to hold Nazi beliefs, but they don't have the right to harm the people they hate. Rapists and abusers have the right to think whatever twisted disgusting things they want, but they don't have the right to harm people.
Gays aren't taking anything away from anyone or harming anyone in either their thoughts or their actions.
Romantic, civil, or business partnerships of legally consenting, mentally capable, and non-coerced adults should not be restricted by anything at all.