a slightly modified version of Appeal to permanent unknowability can be quite legitimate IMO, make it into Appeal to permanent unknowablity given existing conditions then consider the position that our theories are not accurate enough to conclude the existence of Everett branches-or competing theories if one supports them-beyond mathematical abstraction, this seems quite a reasonable position to me-though I'm not so well versed in QM.

on the other hand Appeal to inescapable assumptions seems to be what Eliezer used to be in favor of them being an accurate description of reality. that, or I'm missing something?

EDIT: I agree with byrnnema here

This is an uncharitable interpretation -- I only believe it in a grouchy way -- but my bias here is that I see empiricism as a huge, impenetrable fortress built on assumptions that are reasonable but not necessary. Interestingly, while appealing to the possession of different assumptions, I probably would appeal to humility, personal choice, .etc.