I wouldn't know how to prove to you otherwise other then to tell you that I have seen these tools show incorrect results for both AI generated text and human written text.

Good thing you had a stochastic model backing up (with “low confidence”, no less) your vague intuition of a comment you didn’t like being AI-written.

I must be a bot because I love existential dread, that's a great phrase. I feel like they trigger a lot on literate prose.