Because it probably was. Pangram say it's too short to be certain but they think 100% of the text is possibly AI.

That doesn't mean the comment is useless, though. There's a whole philosophical discussion to be had here about whether what matters is the comment or the identity of the speaker.

Because it is. Most submissions get 5-10 such comments from new green accounts, and their bio conveniently has a link to their project.