If you take those words "kind" and "curious" in a large sense—larger than usual—I think there's enough room there to talk about even this topic without breaking the guidelines.
How to do this? That is something we have to work out together. You're right that it's difficult.
From a moderation point of view, I can tell you that just avoiding garden-variety flamewar and internet tropes already gets us a lot of the way there. You'd be surprised at how many users who think they're taking a grand moral stand against conventional politeness are simply repeating those. Conventional impoliteness isn't any answer either.
I've posted about this quite a bit, since it inevitably comes up every time this topic appears on HN's front page. Here's another part of the current thread: >>44403458 .
* https://hn.algolia.com/?dateRange=all&page=0&prefix=true&sor...
There are reasonable discussions to be had, but the submissions which might catalyze them are quickly flagged (as opposed to defended, like this one).
Examples:
If you're going to defend how this inflammatory post is some kind of exception to your policies, you're going to have to do a better job.