I agree that MWI doesn't help much in explaining our sensory strings in a Solomonoff Induction framework, relative to "compute the wave function, sample experiences according to some anthropic rule and weighted by squared amplitude." This argument is known somewhat widely around here, e.g. see this Less Wrong post by Paul Christiano, under "Born probabilities," and discussions of MWI and anthropic reasoning going back to the 190s (on the everything-list, in Nick Bostrom's dissertation, etc).
MWI would help in Solomonoff induction if there was some way of deriving the Born probabilities directly from the theory. Thus Eliezer's praise of Robin Hanson's mangled worlds idea. But at the moment there is no well-supported account of that type, as Eliezer admitted.
It's also worth distinguishing between complexity of physical laws, and anthropic penalties. Accounts of the complexity/prior of anthropic theories and measures to use in cosmology are more contested than simplicity of physical law. The Solomonoff prior implies some contested views about measure.
Series: How to Purchase AI Risk Reduction
Another method for purchasing AI risk reduction is to raise the safety-consciousness of researchers doing work related to AGI.
The Singularity Institute is conducting a study of scientists who decided to either (1) stop researching some topic after realizing it might be dangerous, or who (2) forked their career into advocacy, activism, ethics, etc. because they became concerned about the potential negative consequences of their work. From this historical inquiry we hope to learn some things about what causes scientists to become so concerned about the consequences of their work that they take action. Some of the examples we've found so far: Michael Michaud (resigned from SETI in part due to worries about the safety of trying to contact ET), Joseph Rotblat (resigned from the Manhattan Project before the end of the war due to concerns about the destructive impact of nuclear weapons), and Paul Berg (became part of a self-imposed moratorium on recombinant DNA back when it was still unknown how dangerous this new technology could be).
What else can be done?
Naturally, these efforts should be directed toward researchers who are both highly competent and whose work is very relevant to development toward AGI: researchers like Josh Tenenbaum, Shane Legg, and Henry Markram.