Japanese culture has used symbols (not kanji, more like dingbats) for at least 20 years if not 30 to 35. They use them in business documents all the time. The most common are probably ●○◎■□▲△▼△. In fact like in the USA a generic name might be "Smith" in Japanese they often using 〇〇さん.
Further, they've been using emoji for the last 20 years. So telling them they can't is basically telling all of Japan they're 2nd class. Their standards and ways of communicating don't matter. Lots of programmers from cultures where emoji and symbols were not in common use dismiss them because in their culture they were not in common use just a few years ago but other cultures have been using them much much longer. As such, banning them is unintentionally racist.
I don’t know if “racist” is the right word for what the GP poster meant, but there’s certainly a concept of “complaining about something while ignorant of the fact that it isn’t a problem outside of your own particular culture.” Whatever the adjective for that is.
It’s the same property that applies to the people who, 20 years ago, initially argued for UTF-8 specifically because of how efficiently it encodes from-ASCII codepoints, ignoring that for most text in most languages on Earth, UTF-8 is less efficient than UTF-16. (Of course, UTF-8 won out anyway, but more because it’s easier to parse, auto-resynchronizing, not limited to the first 16 planes, and because we ended up inventing all sorts of XML/JSON-based document formats, like ePub and OfficeXML, that cause even documents in other languages to be mostly from-ASCII codepoints by weight.)
It’s also the relevant property for Americans who complain about large downloads for games, or who have cellphone service but don’t have data, and think “the world” needs solutions to these problems, when really, North American ISPs are uniquely horrible (to the point that a game developed excluding North America as a potential target market could probably do things we’d think of as “impossible” right now, like live-streaming mesh co-AR or something.)
Further, they've been using emoji for the last 20 years. So telling them they can't is basically telling all of Japan they're 2nd class. Their standards and ways of communicating don't matter. Lots of programmers from cultures where emoji and symbols were not in common use dismiss them because in their culture they were not in common use just a few years ago but other cultures have been using them much much longer. As such, banning them is unintentionally racist.