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.