Unless we think most information exists in simulations than if you take a random bit of information out of the universe it's more likely to be associated with the root existence's goinings on than it is with any kind of simulation. This works because it's an argument about that bit of information, not anything else. I think you could push back and say that really actually information isn't what's important and that actually even if we think that most information won't be part of a simulation most consciousnesses will be, but idk, that seems suspect, we don't have any reason to think that. Certainly most simulations we do now seem not to include consciousnesses.
I think the idea of Boltzmann brains fall apart because in that sea of possibility space it actually seems much more likely for the seeds of a universe to form than a complete brain full of consistent memories of writing 3/4th of a post on a randomly generated website called hacker news. I think it's just another illustration of the problems apply infinity to probability.
Well, what quantity of information? It seems relatively unlikely that one would bother simulating an entire universe for billions of years at this level of fidelity; what's the point? On the other hand, the quantity of information needed to simulate your current experiences, including the experience of having memories, is probably in the megabytes; human bandwidth just isn't that high.
The same logic suggests that, even if you discount simulation for reasons of faith or whatever, Boltzmann brains are worth considering. The idea that the experience you're having right now of reading my precious prose is worth keeping a universe running, or even a large-scale simulation, is a bit self-centered of you, isn't it?