As Eliezer discuses in the post, Reality Fluid isn't just for Many Worlds, it also relates to questions about [simulation].

Only as a side-effect. In all cases, I suspect it's an idle distraction; simulation, qualia, and born-probability models do have implications for each other, but it's unlikely that combining three tough problems into a single complicated-and-tough problem will help gin up any solutions here.

Here's my argument for why you should.

Give me an example of some logical constructs you think I should believe in. Understand that by 'logical construct' I mean 'causally inert, nonspatiotemporal object.' I'm happy to sort-of-reify spatiotemporally instantiated properties, including relational properties. For instance, a simple reason why I consistently infer that 2 + 2 = 4 is that I live in a universe with multiple contiguous spacetime regions; spacetime regions are similar to each other, hence they instantiate the same relational properties, and this makes it possible to juxtapose objects and reason with these recurrent relations (like 'being two arbitrary temporal intervals before' or 'being two arbitrary spatial intervals to the left of').