That is a fair criticism. I still think there is a difference in degree between (A) reading a long, thoughtful article and responding with unkind speculations about the author, and (B) reading such speculation that has little content in it and responding in turn with unkind speculations about the comment's author; but only a difference of degree, not of kind, I admit.
> your comment would put a chilling effect on frankly discussing other people, as though the only way to do so is through irrationality and gossip.
The proverb I quoted would do that, sure, which is why it's explicitly marked as only a decent (not excellent) heuristic. There are honest, thoughtful ways to go about discussing and criticizing people. Speculations and borderline conspiracy theories are not among them.
It also doesn't apply here, because the grandparent comment is not trying to refute PG's argument, it's mounting an entirely orthogonal one. So yes, I do agree it's not directly discussing the content. But that's also pretty characteristic of most HN threads.
People on HN usually talk about the ideas they have which are evoked by the article. They do not as a rule engage in formal refutation or advocation of the article's core thesis, unless it's very technical in nature.
This is to say that I reject the premise; your comment would put a chilling effect on frankly discussing other people, as though the only way to do so is through irrationality and gossip. People can critically discuss other people in an intelligent way without having "small minds", and you shouldn't attempt to infer a person's overall "mental state" from this kind of commentary, in my opinion.