I agree with everyone else: superposition with rocks does not produce "garbage" in any sense that would make a person-simulation sufferingless if it wasn't before.

In particular, note that for the particular case of quantum superposition, what you are describing is basically the same thing that in other contexts goes by the name of "many worlds": the person-simulation and the rocks-simulation evolve independently enough that it's at least defensible to think of them as happening in separate universes.