"They" can be used as singular in the English language.

You seem to be focusing on what's obviously not the focus of the commentary. Which is an interesting data point in and of itself.

That's not a plural, it's the standard English pronoun for a person whose gender isn't specified.

That's interesting, because when I learned English in school the pronoun for "a person whose gender isn't specified" was he.

Must have been a long time ago, because efforts to remove "he" as the default gender have been ongoing for years (80s?) and everybody has more or less settled on they rather than the awkward he/she.

You are in a bubble if you think that "everybody has […] settled on they".

https://news.ycombinator.com/item?id=21179524

> All natural languages I know are gendered the same way English is.

Finnish has always been gender-neutral: https://finland.fi/han/article/

Chinese and Japanese also do not have grammatical gender. Chinese imported gendered pronouns about a century ago for ease of translating Western gendered languages, but both languages tend to either refer to people by name or have no word at all and infer from sentence structure.

True, it was a long time ago. I studied English in high-school in the 90's.