The first part of my answer will answer your point about Bekenstein’s limit. The second part of my answer will concede your point, and look at the logical consequences.
In our assumptions, the Bekenstein’s limit theorem is false. This theorem fundamentally assumes that the universe is pixelated, that it is possible to separate it into finite parts. But, in Proposition 5 bis, I assume that real numbers exist. It is basically a limited version of platonic realism. I consider the universe to merely be a mathematical structure. In the end, there is a fundamental chasm between reality itself, and the theories we can make about reality. My opinion is that physics is not the study of reality, but rather, the study of what we are able to measure and the informational patterns we are able to infer from those measurements. That would make the Bekeinstein’s limit a fundamental limit on physical epistemology rather than on ontology.
The hypothetical aliens wouldn’t need to merely flip a quantum coin a bunch of times. They’d need to do that across all the spacetime they are simulating. I think that, because quantum states involve uncountable infinities rather than countable infinities, that it would not be possible for a quantum computer to calculate “more” than a linear sum of infinities that depends on the volume of spacetime/energy that defines the computer’s upper limit of computation. By using a binary computer it is fundamentally impossible to simulate those things, because binary computers can only calculate “countable infinities”. However, my reasoning is shaky, because I do not have the mathematical prowesses necessary to, actually calculate all those things. Basically, aliens would be using some kind of analogical computers in order to force the universe to do the dirty work of calculations for them rather than trying to create an algorithm that does it.
In such a case, simulating a whole person… Could be possible. With a big enough quantum computer that would neutralize infinities using other infinities. In all honesty, you may have gotten me with this. There is no way for me to prove that broken simulations would vastly outnumber the “normal” ones. But, in that case, “waking up again” after your death is still inevitable from your own perspective. You’d have a random mix of both (infinite?) alien simulations (both broken and unbroken. But you’ll be at their complete mercy, if they want to torture you for fun they can) and infinite disembodied reincarnations of a few yottoseconds.
Now, I’ll look a the consequences if I concede your point. Here is the massive problem : as your simulation “ages”, in order to compute the older version of yourself accurately with all the memories it’ll take more and more computing power until it will eventually exceed what any civilization is capable to do. However, the universe is not bound by those limits, since it is infinite. Therefore, as you get reincarnated more and more, the odds that an alien civilization happens to reincarnate you become more and more impossible. Because everyone has eternal life (from the point of view of a deceased time does not pass), the more time passes, the worse the conditions for reincarnating get.
It seems we are done for this particular debate. I would like to thank you for all your thoughts, which have been a precious help, and for giving a chance to my essay despite its negative karma.
If anyone has good counterarguments, on failures from my reasoning, I would gladly take the time to see if they are valid or if they can be refuted.