I agree with the question. It may make sense to attach "probabilities of existing" to universes arising in a chaotic inflation model, but not, I think, in an "ultimate ensemble" multiverse, which seems to be the one being examined here.

But, to be honest, I had never even considered the possibility that a particularly large bubble universe might contain a simulation of a much smaller bubble. Inflation, as I understand it, does make it possible for a simulation of one small piece of physical reality to encompass an entire isolated 'universe'.