I'm agnostic on the simulation question. The ambiguity about whether our reality supports simulations makes this line of reasoning pretty weak.

Also, perhaps I missed something, but couldn't there be more bottom cases than no-simulation cases? The counting exercise didn't quite land.

When you ask what the odds are of a universe supporting rational life, which of course we can't know, there's an important condition on the probability. Only that type of universe can host the question, so the probability of living in such a universe is one (conditional on someone having asked the question).