IIRC, I don't think he's said he's getting Romo ready to play. I believe it was more along the lines of "We need to see what we've got". That was important for the contract extension, IMO.
It has nothing to do with personal preference. The best player plays, always, with Parcells. When it is definitive that Romo is the best player, he'll be in, immediately. I think Bledsoe knows that, and I think that's in the back of Parcells' mind right now. But two uncharacteristic games for Bledsoe isn't enough to make that call, ya know? That's knee-jerk, and could do damage to the clubhouse, considering how popular Drew is. If he keeps it up, the move will be easy, warranted, and understood by all.