My impression is that anything you can simulate via a program could just as well be the fundamental laws of physics -- and vice versa.

The idea behind this line of inquiry - which I hope is continued - seems to be assuming that, if we are simulated, then we are simulated using a similar computation model to our own, and using data structures that we would have come up with ourselves. I don't have better suggestions for which model to use, but it's good to keep in mind that even if one model of a simulation fails to match our physics, then there may just as well be another that does match it.