They, them, and other indefinite pronouns are only really wrong if you wish to follow an 18th century change to the language. Using the word in this context is even older, and I've seen it making a comeback thanks to gender identity awareness spreading here. I've been a big supporter of this and started doing it, where before I would use he as privileged as that seemed to be.
https://youtu.be/d7k-20y5WKU
Then again, English used in areas like Africa or Portugal might have its own rules and it's wrong that way. My $.02