In my experience, if a man and a woman punch each other in the face, telling "she started it" to the police rarely works in the man's defence, even if she really did. Perhaps that's sexist, but that's how the society is, and pretending it's not isn't going to help.
I don't think the deleted answer was genuinely offensive. Maybe that's just because I'm not the target group, however, I feel it was written in an attempt to share one's opinion on the subject, not to belittle and insult women. Also, there's a long stretch between "only intervene if a man is attacking a woman" and "women can't stand for themselves" (or whatever statement was considered sexist), which is not what the answer was saying.
I totally understand how controversial posts are annoying to moderators because of the numbers of flags / comments they generate, but I don't see why the answer has to remain deleted once the question went off the HNQ and cooled down.
Deleting an answer like that sets a dangerous precedent where people choose to be offended by facts rather than rudeness, harassment or bullying, and a post is deleted on those grounds. I fear that if this practice gets enough approval, we will see more unpopular posts deleted under similar pretext. For example, lying about one's illness / pregnancy / homosexuality can in a similar way be seen discriminatory / sexist / homophobic. I may not like such posts and I understand how they can be troubling to read for the respective groups, but I'm even more troubled when the line between "I don't like this post" and "This post is against the rules" is being washed out.