Some minds are more likely to exist and/or have easier-to-satisfy goals than others. The AI would choose to benefit its own values and those of the more useful acausal trading partners at the expense of the values of the less useful acausal trading partners.
Also the idea of a positive expected value is meaningless; only differences between utilities count. Adding 100 to the internal representation of every utility would result in the same decisions.
Suppose we could look into the future of our Everett branch and pick out those sub-branches in which humanity and/or human/moral values have survived past the Singularity in some form. What would we see if we then went backwards in time and look at how that happened? Here's an attempt to answer that question, or in other words to enumerate the not completely disastrous Singularity scenarios that seem to have non-negligible probability. Note that the question I'm asking here is distinct from "In what direction should we try to nudge the future?" (which I think logically ought to come second).
Sorry if this is too cryptic or compressed. I'm writing this mostly for my own future reference, but perhaps it could be expanded more if there is interest. And of course I'd welcome any scenarios that may be missing from this list.