It's a hard comparison to make. Nuclear weapons have caused, and care capable of causing, more damage. But they also have a better safety record, insofar as accidents at nuclear power plants have done more damage to surrounding communities than accidents at places where nuclear weapons are stored.

IOW, one could argue that the metaphor is making nuclear power plants out to be safer than they are.

It's true that coal is awful, too. But I think that it would be callous to simply dismiss the rather arresting psychological impact of entire communities being rendered uninhabitable at a single stroke. Why what happened to Pripyat or Fukushima is known to basically everyone, while what happened at places like Aberfan and Centralia seem to have become subject matter for Atlas Obscura, I couldn't quite say. Perhaps it's the greater scale of the individual events.