Seems to me the commenter was asking: what observations led us to conclude that original affirmative statement that “the AI did this entirely on its own”.

Given that this is a common technique and not a novel invention, it’s probably present in the training set.

The “surely” reads like it’s referring to the presence of that information in the training set. But your response casts it as saying “surely the AI has not invented something on its own”.

The original question stands IMO, the burden of proof is on whoever is asserting that the AI has invented something on its own, with or without training data that surely already mentions this approach