science

I didn't read the whole thing, just got far enough to understand one of their fundamental assumptions is that a universe outside a simulation follows the same fundamental laws of nature as ours

If we are in a simulation, anything outside of it is effectively unknowable. It would be like a self-aware sim in The Sims determining they are not in a simulation because it is impossible for computers to simulate anything -- computers only raise the entertainment stat (I don't actually know what they do in modern incarnations of the game)