Even if humans were to colonize the entire Milky Way, the interactions between two neutrons 13 billion light years away would still be completely outside the sc

Even if humans were to colonize the entire Milky Way, the interactions between two neutrons 13 billion light years away would still be completely outside the scope of the simulation, because those interactions would have no hope of being detected by a human. So you'll always have massive savings versus simulating the entire universe. It's really human computing where it all falls apart.