Yes. Should one worry if his neighbor's just bought a gun? Especially if that neighbor told you that he would shoot you? Perhaps. But does it mean that you should bomb his house some night?
Well we're not talking about one man with a gun. We're talking about the potential for nuclear war. So yes, if the danger is nuclear war, I would say bombing his house would be justified. Wouldn't you?

In America, we can just trot down to the gun store and buy whatever we need. All of our neighbors have guns. Which may help to explain why Americans do not easily trust each other, and often do not even speak to their neighbors or know their names.
Not sure if you're being sarcastic here. Perhaps where you live it is more common to own a gun, but I literally don't know a single person whom I know well that owns a gun.