I really like this answer, thank you, it gives me something to think about.

Why are we sure that mathematics is not completely a part of this time-space bubble?

Let's say there is an "outside" for the mathematics similar to warp space in wh40k.

A "something" where natural numbers, for example, cannot exist, there will be no space or time in such a case, but it may still exist in some weird sense of undivided consciousness.

In such a case for this outside you need a proper rule based bubble to say that there exists a mathematical possibility for our universe to run in according to rules defined inside that bubble.

That would be "simulation space", if we contrast it with the "outside".

I hope I've got my thought across, because I am pretty rusty in my English writing skills.