I believe that is his point.
He's saying "gender" exists independently of "gender roles." He's got it wrong. Sex exists independently of roles. Outside the context of grammar, "gender" is nothing but roles: it's how a society expects people of different sexes to act.
To the extent that "sex roles" exist, they are strictly reproductive. Men inseminate. Women are impregnated, they gestate, they deliver babies, and they lactate. Beyond that, for just about any verb that you wanted to tack onto the subject "Men" or "Women" ... that is, "gender roles" ... you can find an exception in living or historical anthropology.