"Species can't evolve, that violates thermodynamics! We have too much evidence for thermodynamics to just toss it out the window."
Just realized how closely your argument mirrors this.
Er.. what? Evolution doesn't violate thermodynamics.
Bad analogies don't count as solid arguments, either. The difference between evolution/thermodynamics example and your case is that the relation between thermodynamics and evolution is complicated, and in fact there is no contradiction. While it's evident that your idea works only if you can acausally influence something. That's much closer to perpetual motion engine (direct contradiction), than to evolution (non-direct, questionable contradiction which turns out to be false).
A self-modifying AI is built to serve humanity. The builders know, of course, that this is much riskier than it seems, because its success would render their own observations extremely rare. To solve the problem, they direct the AI to create billions of simulated humanities in the hope that this will serve as a Schelling point to them, and make their own universe almost certainly simulated.
Plausible?