Before seeing this I thought you rejected all priors based on Kolmogorov complexity, as that seemed like the only way to save your position. (From what you said before you've read at least some of what Eliezer wrote on the difficulty of writing an AGI program. Hopefully you've read about the way that an incautious designer could create levers which do nothing, since the human brain is inclined to underestimate its own complexity.)

While guessing is clearly risky, it seems like you're relying on the idea that a program to simulate the right kind of "omnipotent, omniscient being" would necessarily show it creating our laws of physics. Otherwise it would appear absurd to compare the complexity of the omni-being to that of physics alone. (It also sounds like you're talking about a fundamentally mental entity, not a kind of local tyrant existing within physics.) But you haven't derived any of our physics from even a more specific theistic hypothesis, nor did the many intelligent people who thought about the logical implications of God in the Middle Ages! Do you actually think they just failed to come up with QM or thermodynamics because they didn't think about God enough?

Earlier when you tried to show that assuming any omni-being implied an afterlife, you passed over the alternative of an indifferent omni^2 without giving a good reason. You also skipped the idea of an omni-being not having people die in the first place. In general, a habit of ignoring alternatives will lead you to overestimate the prior probability of your theory. And in this case, if you want to talk about an omni^2 that has an interest in humans, we would naively expect it to create some high-level laws of physics which mention humans. You have not addressed this. It seems like in practice you're taking a scientific model of the world and adding the theistic hypothesis as an additional assumption, which - in the absence of evidence for your theory over the simpler one - lowers the probability by a factor of 2^(something on the order of MIRI's whole reason for being). Or at least it does by assumptions which you seem to accept.

Maybe the principle will be clearer if we approach it from the evidence side. Insofar as an omni^2 seems meaningful, I'd expect its work to be near optimal for achieving its goals. I say that literally nothing in existence which we didn't make is close to optimal for any goal, except a goal that overfits the data in a way that massively lowers that goal's prior probability. Show me an instance. And please remember what I said about examining alternatives.