Sorry for probably being too sharp.
So, we have a choice: to deny a very counterintuitive statement or to deny causality. Do we have enough evidence to choose the latter? IMO, certainly, no. Anything we have are some thought experiments, which can be misinterpreted or wrong, and contain a lot of hand-waving.
Reformulating in bayesian terms: prior probability for your statement being correct is extremely tiny, and there is almost no evidence to update on. What to do? Reject.
So, we have a choice: to deny a very counterintuitive statement or to deny causality.
I'm not 'denying causality', I'm pointing out a way around it.
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?