Do you buy that in this case, the aliens would like to make the deal and thus UDT from this epistemic perspective would pay out?
If they had literally no other options on offer, sure. But trouble arises when the competant ones can refine P(takeover) for the various planets by thinking a little further.
maybe your objection is that aliens would prefer to make the deal with beings more similar to them
It’s more like: people don’t enter into insurance pools against cancer with the dude who smoked his whole life and has a tumor the size of a grapefruit in his throat. (Which isn’t to say that nobody will donate to the poor guy’s gofundme, but which is to say that he’s got to rely on charity rather than insurance).
(Perhaps the poor guy argues “but before you opened your eyes and saw how many tumors there were, or felt your own throat for a tumor, you didn’t know whether you’d be the only person with a tumor, and so would have wanted to join an insurance pool! so you should honor that impulse and help me pay for my medical bills”, but then everyone else correctly answers “actually, we’re not smokers”. Where, in this analogy, smoking is being a bunch of incompetent disaster-monkeys and the tumor is impending death by AI.)
“last minute” was intended to reference whatever timescale David would think was the relevant point of branch-off. (I don’t know where he’d think it goes; there’s a tradeoff where the later you push it the more that the people on the surviving branch care about you rather than about some other doomed population, and the earlier you push it the more that the people on the surviving branch have loads and loads of doomed populations to care after.)
I chose the phrase “last minute” because it is an idiom that is ambiguous over timescales (unlike, say, “last three years”) and because it’s the longer of the two that sprung to mind (compared to “last second”), with perhaps some additional influence from the fact that David had spent a bunch of time arguing about how we would be saved (rather than arguing that someone in the multiverse might pay for some branches of human civilization to be saved, probably not us), which seemed to me to imply that he was imagining a branchpoint very close to the end (given how rapidly people dissasociate from alternate versions of them on other Everett branches).