Earlier quoted context omitted.
Well, these things are subject to interpretation, of course, but I don't think it's a stretch to call the following a personal attack, as it creates a pejorative image and applies it to the other person (and adds negative intensifiers like "of course", "just", "got emotional", "secretly resented"): " I presume you said nothing to alert her to the issue, of course? Just got emotional about it and secretly resented the…
So how would you have conveyed the intent of, "I don't think you're being fair to this woman, nor do I think you're attempting to engage with the problem you've described in a productive way."? And no, I wouldn't say you've "offended me" per se, just that I find it disappointing you've chosen me, of the two people here, to reply to.
I would stay away from remarks like "nor do I think you're attempting to engage with the problem you've described in a productive way"—that's already a swipe, and already personal, and therefore on the wrong side of the line by HN standards.
The GP comment wasn't great: it was ranty; the repetition of "lady" struck me as slightly distasteful; and the self-congratulatory reference to "unpopular opinion" is one of the worst internet clichés. However, I don't see that it broke the site guidelines; or at least not badly.
If I were going to reply as a mod to every comment that strikes me as bad...well, that would be physically impossible, plus would generate an endless firestorm from readers objecting to my interpretations. I have to be a lot more cautious than that! In practice that means sticking to cases where the majority of readers would likely agree that the site guidelines were broken unambiguously. That's still guesswork, but less guessy than it sounds.