I chuckled, but isnt godzilla product of the nuclear aftermatch?

Yes, and on multiple levels of meaning too.

I think it could go either way depending on how genre-savvy the character is, in the story-document being emitted by the LLM.

For example, perhaps the Kaiju-flavored narrative demands that Military Bigwig dismisses Concerned Scientists' desperate pleas, and empowers the monster by attacking it with a nuclear weapon. Not because it's a strategically (in)correct choice, but because it "fits" with a story trying to make its subtext clear.

True. In the West, nuclear radiation creates super heroes, while in Japan, it produces devastating kaiju.

I wonder what accounts for the difference?