Ok, those are indeed a reasonable class of decisions to consider. Now, you say that CDT loses. Ok, loses to what? And presumably you don't mean loses to opponents of your preferred decision theory. You mean loses in the sense of doing less well in the same situation. Now, presumably that means that both CDT and your candidate are playing against the same game opponent, right?
I think you see where I am going here, though I can spell it out if you wish. In claiming the superiority of the other decision theory you are changing the game in an unfair way by opening a communication channel that didn't exist in the original game statement and which CDT has no way to make use of.
Well, yeah, kind of, that's one way to look at it. Reformulate the question like this: what would CDT do if that communication channel were available? What general precommitment for future situations would CDT adopt and publish? That's the question TDT people are trying to solve.
A monthly thread for posting rationality-related quotes you've seen recently (or had stored in your quotesfile for ages).