Probably worth noting that part of nukes being censored in some Japanese versions of media is whether or not it's going off in a populated area. Final Destination or Battlefield might be considered fine but New Donk City would be a hard no.
The more I think about it after saying it on the last page the more I feel like locking characters in a vault may actually be the best possible scenario for a Vault Boy FS. Notably because it could also give the Smash version of the Vault Boy a distinct number, which would completely evade possible issues of whether to use Vault 13, 111, 101, 21, etc as the Vault Boy's number.