A model doesn't have to be deterministic, use finite quantities, or even be possible to execute in a simulation. Math often does not concern itself with such things. Undecidability is concerned with the set of rules themselves. Even if it is impossible to actually simulate, is there a finite set of physical laws which drive all things? If yes, and if you can construct the basic requirements for counting and making logical statements and such within that system, then you are subject to incompleteness.
That said, it's interesting to think about a universe with truly infinite rules. Each physical law could have minor exceptions caused by smaller more detailed phenomenon. Each time you would discover some new principle, it would reveal more yet unknown questions, a fractal of infinite knowledge to be refined and science to do. But I think most scientists hope for a finite set of underlying rules for reality.
That said, it's interesting to think about a universe with truly infinite rules. Each physical law could have minor exceptions caused by smaller more detailed phenomenon. Each time you would discover some new principle, it would reveal more yet unknown questions, a fractal of infinite knowledge to be refined and science to do. But I think most scientists hope for a finite set of underlying rules for reality.