There are way too many voters on FR who dislike the fact Santorum is a real unapologetic Catholic for them to accept him as a VP candidate. That doesn’t mean he is not a good or viable VP candidate.
Santorum blew it here when he defended the indefensible Specter and snubbed Toomey. Most only recently became aware of his questionable religious tendencies, and I do not believe that they even come into play for him. Its his tendency to go with the establishment over common sense.