but more than that, it knows that the real universe is capable of producing intelligent beings that chose this particular world to simulate.

Good point -- this undermines a lot of what I wrote in my update 1. For example, I have no idea if F = m d^3 x / dt would result in a world that is capable of producing intelligent beings.

I should at some point produce a version of the above post with this claim, and other questionable parenthetical remarks I made, deleted, or at least acknowledging that they require further argumentation; they are not necessary for the larger point, which is that as long as the only thing the superintelligence can do (by definition) is live in a simulated world governed by Newton's laws, and as long as we don't interact with it at all except to see an automatically verified answer to a preset question (e.g., factor "111000232342342"), there is nothing it can do to harm us.