Letting the hack stand means the chain comes to a halt and all value is destroyed? Even if you’re a staunch bitcoin purist, I don’t think that’s the path you want to go on.

The chain wouldn't halt because mining won't be affected by quantum. If you see hacks happening you could race to move your coins into a PQ wallet before the hackers do. I'm assuming that PQ software will be available before the hacks. I agree that this is a very bad scenario.