This has been possible if not easy to accomplish for a very long time, so calling it "AI" seems like a bit of a stretch. I suspect most people can be fingerprinted according to a handful of less typical grammatical flourishes and reuse of certain uncommon words and turns of phrase. The only real challenge is scaling that up.
Sure, but there's always room to advance the state of the art. And in the article, they mention using the adversarial AI approach, which I would say is firmly in the world of AI, and not just statistical analysis.
