I wanted to present you with a nice, sharp dilemma between rejecting the scientific method, or embracing insanity. Why?

Rational agents should WIN. Not lose scientifically, or socially acceptably, WIN. :-)

I hope you talk about normative implications eventually, address bambi's point, so we know just why this mistake matters. (Well, actually, implications of multiverse theories generally, so MWI doesn't practically matter if we live in a multiverse for some other reason.)

The scientific method has trounced logical argument time and time again.

Humans need empiricism as a check because we're, in absolute terms, pretty bad reasoners. Eliezer's "Science" (which is a bit of a strawman, but excusable) goes too far in the right direction from overconfident pure rationalism. (I believe this is the point of the Aumann example, maybe even of the whole post.) This should diminish confidence in pure logical argument, even where experiment is silent, but the case for MWI still looks strong to this non-physicist.

Computer programs in which language? The kolmogorov complexity of a given string depends on the choice of description language (or programming language, or UTM) used.

This confuses me as well.