Speaking for myself, I don't believe this is a matter of personal hatred or any unified party ideology. Santorum obviously does not hate his daughter nor other disabled people, and there are Republican Senators that voted in favor of ratification. I do think that the concerns about the treaty somehow trumping U.S. law or being automatically enforceable in American courts are, given the specifics of the treaty and recent American jurisprudence, completely unwarranted. But I don't believe the opposition is rooted either in personal animus of any kind, nor in any uniform party ideology.
This is the most reasonable post I've seen in a long time