Cool way of putting it. Let's run with that. A good actor can be seen as instantiating a Boltzmann Brain while on stage -- especially when improvising (as always may be needed). Maybe each of us is instantiating some superposition of Boltzmann Brains in everyday life as we wend our way through various social roles...

From now on I'll listen for the subtle popping sounds as these BBs get instantiated and de-instantiated all around me...

Of course a philosopher can object that (1) these BBs are on a substrate that's richer than they are so aren't "really" BBs and (2) they often leave traces that are available to them in later instantiations which again classical BBs can't. So maybe make up another name -- but a great way to think.