Wow, this is such a wrong way of interpreting the way things are, that you're finding offense where none was probably intended.
Have you ever witnessed the "eww, foreign shit" thought process, or did you invent this in your head? Emojis are used all over the world that I can't imagine anyone thinking they're a "Japanese thing". Yeah they're from Japan but your imaginary racism accusation is so weird to me, if it's real, to me it would be like meeting someone who does not use flush toilets because s/he doesn't like the British.
There are technical reasons for not supporting Unicode, e.g. to prevent garbling like https://www.zalgo.org/ , but throwing things like "not supporting emojis (I'm going to mansplain to you that emojis is part of Unicode) is sexist is just... Argh! For your own sake, I suggest you stop it with the identity politics and looking to be butthurt by any perceived offense, it won't lead to a life of happiness, and you'd be the irrational one who's looking for conflict, sadly while believing you're the sane one in a holy crusade against infidels. (Ha, for the sake of analogy, it's just like Isis/Al-Qaeda think they're the righteous ones whereas the rest of the world sees them as the bad guys).
I don't know why I want to save people from themselves in an HN comment box, but here's me trying. Although I think you're already so offended that you'll totally ignore this.