The problem with this is that the word 'hot' only has meaning to a conscious being. And while we don't know what conciousness is, it's extremely hard to argue it's not an emergent property of physics. So if your supernova simulation is complex enough to also model emergent properties like conciousness, the simulated conciousness may well regard the supernova as 'hot'.
Ya and this leads to the point that if the simulation is so complex, which I take to mean is so like the real thing, then the near-perfect simulation and the actual thing must be highly similar physically.
And digital circuits are not physically similar to biological brains yet. So we shouldn’t conclude they have the similar consciousness property.
That would imply that the biological physical substrate is necessary for conciousness, which I don't think you can say with any degree of certainty. It's not an assumption I would personally make. And while I'm speculating, my own view is that whatever the eventual subjective experience of what it's like to be an AI is, it will be nothing like the experience of what it's like to be a human, regardless of the fact we're training them to interact in human-like ways.
Funny you mention simulations. The simulation theory that we all live in simulations doesn’t have any practical consequences for me or any one.
If our world behaves exactly the same, what difference does it make?
The perspective. From within the simulation there is no point in making the distinction, but from the outside it does. For another example - running a program on a virtual machine or a physical computer is the same to the program, but very different to debug when you see hardware errors.