The issue isn't "status as a morally worthwhile person" but strategic position.
It's true that a sim and an original could agree that what happens to the original is all that matters. Such a sim will sacrifice itself willingly if doing so implies a greater chance that the original gets what it wants.
But the essay in the OP stipulates what the RAI values, and these values mean that there is no strategic value to caring only about what the original gets. Both the sim and the original just want to see computation C completed. The completion of C is something that the RAI could complete in either possible world. Even if the RAI is a sim, its computation of C would be completely real. There would still be a real hardware substrate somewhere that ran through the computation of C, even if that hardware were simultaneously creating an AI who thinks that it's 2040.
This means that the possibility that the sim will be aborted really is a threat to something that the RAI, in both instantiations, values. So, the RAI ought to weigh this possibility.
::laughing with pleasure::
Yes, in that particular contrived example the boundaries between daydream and real accomplishment are potentially blurred if the difficult accomplishment is to have successfully dreamed a particular thing.
But while dreams within dreams are fun to play with, I don't think that a coherent theory of simulationist metaphysics can ignore the fact that computation in a substrate is a physical process. Rolf's RAI might have an incoherent theory of computation, but I suspect that any coherent theory is likely to take into account energ...
http://www.sl4.org/archive/0708/16600.html