You have misunderstood if you think I said that “the other entity’s physics cannot be more than quantum”. I am arguing that if the simulating universe is not quantum mechanical it is so fundamentally different that it cannot resemble our world, and that means that the simulators cannot be descendants of the people we are simulating because that universe will not contain people. It won’t contain carbon! Which would make this not a simulation as such but some kind of constructed reality no different from the dream of a demon. I admit it could be such a thing. I merely argue we have no reason to think it based on the laws of quantum physics or Bostrom’s arguments.