"Gender is a word to be applied to grammar, not people. If someone is female, that is her sex, not her gender. (The gender of Mädchen, the German word for girl, is neuter, as is Weib, a wife or woman.)"
That's doing some pretty hard core identity theory without a license. What would Judith Butler say?
That's not identity theory; it's just a definition. That said, you can use "gender" in situations where using "sex" would cause uncomfortable atmosphere, correctly or no, so there's no way we're getting that distinction back.
There's another context: gender can mean the psychological and social aspect of sexual identification. I believe that's what the "identity-theory" bit refers to.
That's doing some pretty hard core identity theory without a license. What would Judith Butler say?