The statement that "every non-zero thing has to happen" in this context obviously refers to the wavefunction of QM.

Clearly, that was not obvious to me. There is a common misunderstanding that many worlds implies that "everything is possible," and that statement seemed to match this pattern.

I thought it was generally accepted that simulation is possible...

It is accepted by many, but it has not been demonstrated to the level where solely postulating many worlds qualifies as an acceptable argument for your point.

I never said that this would equate to actual truth of any religion.

I am not sure how else I could have been expected to interpret "then all religions has to be true (in a simulation)."