There is a difference between a game depicting some reality where there is sexism, and a game made by sexist people who promote sexism.
That's why the sexism rating should be two ratings:
One rating for how much sexist clichés there are in the game, has there are in real life.
One rating for how much the game could induce sexist behavior, as it may be done on purpose by sexist people.
(this late posting is more a note to myself...)