Personally, I'd love it if he did, although I'm not crazy about Tom Ridge for other reasons, particularly including his association with the incumbent Administration and his embrace of the pro-bureaucracy Homeland Security Act. Still, I'm pro-choice and I think the point needs to be made forcefully that pro-life politics need not dominate and control the Republican Party.
A plurality of Republicans and a majority of Americnas are pro-choice, defined as being opposed to a general ban on abortions (even with limited exceptions). That leads me to believe that pro-lifers exercise disproportionate control over the party, particularly through activism in the primaries. This means that the party's leaders and nominees do not accurately reflect the political desires of the party's members -- rank-and-file Republicans are, at best, divided on the issue.
But I rather doubt it will happen. Get above the level of rank-and-file, the ordinary people whose only political activity is to vote, and you start filtering out the pro-choice people. Party activists are activists largely because they care about issues, and pro-life activists have only one party at which they can direct their energies since there are so few pro-life Democrats and a pro-life stance is so profoundly out of step with the national party. Party leaders gain power by appealing to party actvists, not to rank-and-file members, and by raising money -- again, by appealing to people who care intensely about particular issues. The miracle of pro-choice Republicans is that any of them manage to get nominated at all.
Pro-choice Republicans could, in theory, take control of the party -- if they had a leader who could rally them around that cause, if they could motivate themselves to care enough about the "big tent" to assert themselves. The last best hope of anything like that happening in this election cycle, however, was Rudy Giuliani's campaign that went down in flames in late January of this year. Hizzonner had started to waffle on that issue anyway, which I thought at the time was a mistake. Nevertheless, I think there are enough pro-choice Republicans that would add votes to the McCain column would offset the number of pro-lifers who would withhold their votes come November -- those voters, frankly, will work themselves up into an anti-Obama frenzy and hold their noses for McCain. They have nowhere else to go come November and by now, they're too well-trained to not vote. (No wonder their votes are being taken for granted; this bloc of voters are the victims of their own success.)
But looking at the list of available pro-choice Republicans of any prominence who might be picked as credible VP choices for McCain, I'm unhappy with them all for other reasons. Mitt Romney is no longer pro-choice. Tom Ridge was Secretary of Homeland Defense and seemed to relish the role of presiding over a burgeoning bureaucracy. Condoleezza Rice is also far too closely identified with the incumbent Administration and the unpopular Iraq war. I'd personally like Rudy Giuliani but given his rejection by the party base in the primaries, it would be difficult to justify him. Joseph Lieberman isn't even a Republican.
The three or four likeliest choices on the table now -- Sarah Palin, Charlie Crist, Rob Portman, and Tim Pawlenty -- are all pro-life. So unless McCain thinks that Ridge can make him competitive in Pennsylvania and creating a ninth battleground, I don't see Ridge being a net benefit. And I'm far from confident that Ridge, although personally popular in Pennsylvania, will be enough of a "favorite son" to pull the Keystone State out of its deep blue funk.