I'm not a libertarian, but I have fond memories of Barry Goldwater (In my heart, I know he was right). And I have respect for, if not agreement with, philosophers like Ayn Rand. But Ron Paul is just -- out there.
I don't want Ron Paul defining what "conservative" means. I don't want him defining what "Republican" means. I don't want to have to expend any energy defending myself or my party from issues raised by liberals concerning Ron Paul's weird and hateful ideas. And I don't want enthusiastic young participants in political life getting detoured into the exile of conspiracy theory advocacy and "faithful remnant" movements, because they've put their faith in this guy.