Except there is no such thing as “Correct English”. If we were speaking about eg contemporary France French, you would have a point - there is a governing body

Except there is no such thing as “Correct English”. If we were speaking about eg contemporary France French, you would have a point - there is a governing body decreeing what is correct French and what isn’t. That is not the case for English. But even that is besides the point, because “they” as a genderless pronoun has been used for over half a millennia. (William Caxton, 1460: “Each of them should...make themself ready”)