It makes technical conversations about Unicode ridiculously annoying. It's working as designed and the design is broken.
Whether the absence of emojis on HN is a feature or a bug is arguable. But if you can't figure out a way to work around this constraint (e.g. put your example literally anywhere else on the web and post a link here) HN is probably not a good fit for you.
Reading a discussion thread where each message is just a link to some pastebin with the actual message isn't very nice. Besides, I wasn't going to write the message again after HN removed arbitrary parts of it, hence the edit; I think people got the gist. You may feel that discussion about Unicode doesn't belong on HN but I feel otherwise.
Reading discussion threads full of silly emojis isn't "very nice" either, at least for a certain kind of audience. It's a tradeoff, and the powers that be at HN have decided to optimize for sober discussion over expressivity. It's a defensible decision. Keeping HN from degenerating into Reddit is already hard enough.
I'm sure you'd have survived my unsensored message.
Of course. It's everyone else's emojis that would get annoying.