In the case of GPT2, or any general purpose language transformer, where the purpose is to just mimic human writing, I'm certain there are statistical solutions to find this type of text.

But if the text was created with (currently mythical) General AI, the text itself should be evaluated in terms of whether or not it is valuable. If it's valuable research, it doesn't matter if a person did the research or AI, again, assuming it was produced by a mind, not just a language transformer like these examples.