You seriously think that the fact that the creationist doesn't let his abstract belief control his actions is not relevant to the question of whether he will let his abstract belief control his actions?

I think that the fact that he doesn't let his abstract belief cause him to drink poison, when everyone around him with the same abstract belief obviously doesn't drink poison, when common sense (poison is bad for you) opposes the abstract belief, and when the relevant abstract belief probably occupies very little space in his mind* is of little relevance to whether he will let an abstract belief that is highly salient and part of his identity make him act in a way that isn't nonconforming and doesn't conflict with common sense.

*If any; plenty of polls show Christians to be shockingly ignorant of the Bible, something many atheists seem to be unaware of.

So, if you agree he would be willing to cooperate with an atheist, why would he not cooperate by exchanging his choice for the higher payoff in the event that the atheist is right for the atheist's choice for the higher payoff in the event the creationist is right? Recognizing a Pareto improvement is not hard even if one has never heard of Pareto.

No doubt he would, which is why I would try to persuade him, but he is not capable of discerning what action I'll take (modulo imperfect deception on my part, but again I seriously doubt I could do better by internally committing), nor is his decision process correlated with mine.

It seems you are prepared to recognize this. Are you also prepared to recognize that he did not start out superrational, but is persuaded by your arguments?

I would rather persuade him to cooperate but not to be superrational (allowing the outcome to be D/C) than persuade him to be superrational (forcing C/C), and I doubt the latter would be easier.

(Caveat: I'm not entirely sure about the case where the creationist is not superrational, but knows me very well.)