Again, I'm not sure what you mean by "blame" here. If you're saying that Tarski's result represents a problem that affects more than just attempts to generalize Solomonoff induction, then I agree.

BTW, while I have your attention, what's your evaluation of Paul Christiano's FAI design idea, which sort of tries to punt as many philosophical problems as possible (including this one)? I noticed that you didn't comment in that discussion.