I'd imagine yes but more because discrimination is zero tolerance and this is one of those "quiet discrimination" incidences that is clearly sexist if you know what you're looking for (a woman being the target of something that a man wouldn't be targeted for in the same way). Like if a player called a female coach a slag or unf*ckable I'd consider that sex based discrimination. I have sent off a player before for saying someone "looked like a transvestite" on those grounds.That's an interesting point that I was thinking about as I read this thread. Is the fact the abuse was directed at a female coach (in a men's game) swayed people towards a red?
Think I would be looking at her reaction, if she laughs if off and / or gives it back with interest it is going to be very difficult to give a red card there and you're on a hiding to nothing before a ball is kicked. Whereas if she doesn't take it well, looks or sounds offended, it makes the decision that much easier.
Edit: I'm slightly camp and once got called a "powder puff" in my teams purple GK kit, at the time I felt this could have a homophobic undertone but I think there is some benefit of doubt you have to apply.