I'd wager 99.99% of humanity would not want to start a nuclear war by vaporizing millions of people, animals, etc. with a nuke. They'd back away slowly and figure out how to ensure it was safely disposed of so they didn't need to be near it or worry about it.
A very small number of people would like to have a nuke with which to harm other people.
Some of those people even probably got that way because of actions taken by people saying things like "if we don't do it, somebody worse will" and "we are the only ones who can be trusted to control this power"