I think it's naive to think that nuclear weapons are justifiable just because someone else has nuclear weapons.
It starts an arms race and makes the overall situation worse. This type of mindset is literally how we got to this point to begin with. The U.S. built up a stockpile of nukes, to which Russia built one up, to which the U.S. built more in turn, so on, so forth.
So yes, I am of the stance still that no we should not have a nuke. Like I said previously, yes it's bad we're in a situation where the U.S. has nukes and we're left in a position where they're able to use them and we have nothing to dissuade them.
However, just because someone poisoned the punch doesn't mean we should poison it more. Franz Ferdinand's assassination in WWI started a chain of events nobody would have predicted lead to the sheer level of conflict it did. Now imagine that with nuclear weapons being exchanged by small and large countries alike.
Why should we partake in the very activity that got us to this situation to begin with? Just because we have trouble getting the big guys to get rid of them doesn't mean we should throw our hands in the air, give up, and make more of these things.