Wow. To assume that I am sexist from that comment is beyond ignorant. I typed as I normally do and in 90% of America it is the norm to type girl in that sentence. Maybe this is shifting but it is not sexist to type commonly used terms in certain contexts.
Do you genuinely think we should assume guilt on someone because their feelings are hurt? That's a dangerous path to go down and we have to rely on hard evidence or else witch hunts have real consequences.
It's not hard to imagine the tides turning and false acquisitions becoming as big as a problem as sexism.
PS. I am a firm believer in removing sexism from all cultures.