Communities don’t decide to make someone’s gold useless just because they die or don’t protect it properly.
If Satoshi is dead or doesn’t want to upgrade his wallets, then he doesn’t have to. Let him decide his own security choices, just like the rest of us. If his Bitcoin gets taken by a quantum computer, then the new owner will certainly use the new quantum resistant technology. The market will freak out, network security will improve, and Bitcoin will endure like so many times before.