Of course that kind of heuristic can have false positives, and not every accusation of AI-written content on HN is correct. But given how much stuff Gregg has written over the years, it's easy to spot-check a few previous posts. This clearly isn't his normal style of writing.
Once we know this blog was generated by a chatbot, why would the reader care about any of it? Was there a Mia, or did the prompt ask for a humanizing anecdote? Basically, show us the prompt rather than the slop.