In a moral vacuum, I agree. If I could flip a switch and permanently erase nuclear weapons from the world, I think i'd probably flip that switch. However, we don't exist in a world with switches like that. Any weapon the US doesn't develop out of some moral sensibility, another state like Russian or China will. Ceding military strength is not virtuous, it's naive. The choice isn't between "should these weapons exist or not", it's "who should have them?". And the answer to that choice is: the entity you distrust least. For me that's the USG. I distrust them, just less than I do the other candidates.

And this is an extremely critical moral choice, because it's the only real one. Any other choice is just burying your head in the sand and saying the world doesn't exist.