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.

Yes, I think so.

It also sounds like you're talking about a fundamentally mental entity, not a kind of local tyrant existing within physics.

Yes, that is correct.

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?

A few seconds' googling suggests (article here) that a monk by the name of Udo of Aachen figured out the Mandelbrot set some seven hundred years before Mandelbrot did by, essentially, thinking about God. (EDIT: It turns out Udo was an April Fools' hoax from 1999. See here for details.)

Mind you, simply starting from a random conception of God and attempting to derive a universe will essentially lead to a random universe. To start from the right conception of God necessarily requires some sort of observation - and I do think it is easier to derive the laws of physics from observation of the universe than it is to derive the mindset of an omniscient being (since the second seems to require first deriving the laws of physics in order to check your conclusions).

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.

You are right. I skipped over the idea of an entirely indifferent omni-being; that case seems to have minimal probability of an afterlife (as does the atheist universe; in fact, they seem to have the same minimal probability). Showing that the benevolent case increases the probability of an afterlife is then sufficient to show that the probability of an afterlife is higher in the theistic universe than the atheistic universe (though the difference is less than one would expect from examining only the benevolent case).

I also skipped the possibility of there being no death at all; I skipped this due to the observation that this is not the universe in which we live. (I could argue that the process of evolution requires death, but that raises the question of why evolution is important, and the only answer I can think of there - i.e. to create intelligent minds - seems very self-centred)

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.

I question whether it has an interest in humans specifically, or in intelligent life as a whole. (And there is at least a candidate for a high-level law of physics which mentions humans in particular - "humans have free will". It is not proven, despite much debate over the centuries, but it is not disproven either, and it is hard to see how it can derive from other physical laws)

Insofar as an omni^2 seems meaningful, I'd expect its work to be near optimal for achieving its goals.

This seems likely. It implies that the universe is the optimal method for achieving said goals, and therefore that said goals can be derived from a sufficiently close study of the universe.

It should also be noted that aesthetics may be a part of the design goals; in the same way as a dance is generally a very inefficient way for moving from point A to point B, the universe may have been designed in part to fulfill some (possibly entirely alien) sense of aesthetics.

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.

I can't seem to think of one off the top of my head. (Mind you, I'm not sure that the goal of the universe has been reached yet; it may be something that we can't recognise until it happens, which may be several billion years away)