You'll note that increasingly my posts here are on homelessness. There are nearly 600,000 homeless in the US alone, many of whom will die from homelessness-related problems. Many posts on this site both spread misinformation about that problem, and argue against any and all real solutions to that problem. That isn't kind, but it isn't moderated. And treating those comments as if they are not reprehensible, might be kind to the poster, but it's unkind to the 600,000 homeless in the country where a lot of HN users live.
Kindness isn't a simple thing: sometimes kindness to one person needs to be balanced with kindness to other people.
I get that you're using the word differently and that's fine, as long as we understand what each other means by it. It seems like you're defining your political position (on homelessness in this case) as 'kind' while the opposing position is 'unkind'. Presumably someone of the opposite view might take issue with that, but I don't.
Since it's in your interest to argue for your views in a way that is personally kind to the people you're arguing with, I don't see any tradeoff between our two usages.
(1) plenty of HN users post comments from plenty of ideological positions without breaking the site guidelines and (therefore) without getting moderated; and
(2) users breaking the site guidelines from all different ideological positions do get moderated.
That doesn't fit with "you're taking a side". In my experience the causality goes the other way: when people get moderated they have a strong tendency to jump to "the mods are against my side" rather than look at how their posts are breaking the rules and/or go against the intended spirit of the site. In other words it's not "I got moderated because you're taking a side", it's "you must be taking a side, because I got moderated". So it's probably worth adding:
(3) The users who jump to "you're taking a side" are distributed across all the ideologies.
There are also users of every ideological view making the case "my ideology is special; it requires me to break the rules, otherwise it cannot properly be communicated". This is disproven by all their co-ideologists who have no trouble communicating similar views without that.
I agree with you that https://news.ycombinator.com/item?id=40136616 was not as bad as your other three comments I listed, but it still used the "people like you" trope, which is a flamewar + personal attack combo that leads to forum hell.
I don't believe you need personal attack, clichés of internet aggression, etc., to make your case for what you believe in. On the contrary, these things cheapen your position. Morever, they are fungible across all the ideologies—that is,
(4) commenters who resort to breaking the site guidelines resemble each another far more than they resemble anyone else. Ideology is not the high-order bit here.
By the way, I don't identify with your word "politeness". Enforcing politeness in not at all what we're after, and in that sense I agree with you, though I think you're misassessing what we do as mods. Politeness is profoundly uninspiring as a value, and I'd find it profoundly demotivating if that were the principle. But it's not.
The HN guidelines used to say "Be civil", but we changed that years ago to "Be kind", because civility (which I take to be close to politeness) doesn't go deep enough to capture what we want here. Kindness is a far better word. We want people to be in good relational connection with each other, even when they disagree about a topic. That's an ideal, of course, but it's the right ideal for HN, because it's needed in order to optimize for curiosity: https://hn.algolia.com/?dateRange=all&page=0&prefix=true&sor....