Romney's pro-life though. And that will be enough for Christian conservatives to vote for him over Obama, regardless of who the VP is. Hell, Ridge allows Romney to continue to cater to the right on social issues because Ridge will please moderates/independents and send a message of Romney not being a far-right extremist (even if the things that he says indicates otherwise).
I think that people are overestimating Romney's need for a right wing running mate. Romney may not be the most appealing candidate to far right wingers (which is why he had such a tough primary), but they are still going to be out in full force to vote for him. Gary Johnson isn't going to attract all of those voters. The far right wingers will vote Romney because in their eyes it is either him or a Muslim communist. They'll vote Romney. Using the running mate to make a play for independents is the smarter move, IMO.