I’m almost certain Perry does not want Palin in the race. For similar reasons, Romney very likely does.
Then Romney's a fool. He can't win the nomination without the Tea Party vote, and he has ZERO credibility or connection with them. Palin, on the other hand, is the de facto leader of the Tea Party movement, and will handily take most of that vote.
The only vote that Romney can rely on, is the uninformed, last minute R voters, and cross-over Democrats in open primary states. He's not getting the conservative vote no matter what he does.
Frankly, his only path to the nomination is endurance. He'll have to somehow be the last man standing to have a hope of getting most of the Republican vote. I think he'd depress Republican voters so badly, that it might even be close in the general election.