Yeah, one's floating in magma- and none of the others are in places they would be exposed to a direct nuclear blast in the event of nuclear holocaust, either.

And even if they were... the reason the fang and sword (and Fiendfyre) worked is because the criterion for destroying a Horcrux is "damaged beyond magical repair". Basilisk venom and cursed fire both have a distinctly magical quality of "no takebacks". Who knows of being reduced to constituent atoms by mundane means counts? (Probably it does, but it isn't certain.)

But I assume it bothers him because if he wanted humanity eradicated, he could have accomplished it by now. And he didn't seem to take any pleasure in his belief that

"Those fool Muggles will kill us all someday!" Professor Quirrell's voice had grown louder. "They will end it! End all of it!"

[...]

"Yes, nuclear weapons!" Professor Quirrell was almost shouting now. "Even He-Who-Must-Not-Be-Named never used those, perhaps because he didn't want to rule over a heap of ash! They never should have been made! And it will only get worse with time! [...] The eager little fools who discovered the secret of nuclear weapons didn't keep it to themselves, they told their fool politicians and now we must live under the constant threat of annihilation!"