First off: they're not "AIs", they're LLMs.

Second: LLMs spit out what is crammed into them. Nuclear weapons dominated international politics and wargames/simulations and war college navel-gazing for what, 75-80 years or so? Political papers. Fictional works. Society has a TON of popular media about nuclear war.

Why is anyone surprised that LLM responses are very influenced by nukes?