Hm.
Well, it's definitely good that he's doing the intellectually honest thing and expressing the views he apparently actually holds rather than the views it's politically advantageous to him to express, though it surely would have been better had be been willing to do this sooner.
But we're not really concerned with whether he did the right thing or not, are we? We're just concerned with how this changes the race. So:
I don't know whether this is bad for Giuliani or not. However, I will say this:
If this does turn out to be bad for Giuliani, it will immediately turn out to be very, very bad for the Republicans. If Giuliani is taken down because he doesn't toe the "pro-life" party line, this will signal to moderates, nonfundamentalists, log cabiners, civil libertarians, whoever, within the Republican party that this is not their party and they are not welcome there, and the flow of moderates out of the Republican party, which up until now has seemed like just a steady trickle no matter how extreme the party itself gets, may well spike immensely...