Duh, everybody would react with anger if someone knees you in the face...
Defending yourself=validating the idea that men are violent and have no respect for women...sure, as if any women in that situation would react differently.
There is a difference between not treated kindly and being attacked. The first case you can ignore, the second gets an equal response. If reacting in that way gives them further arguments so be it.
You sure as hell don't get respect or stop bullying by being passive and letting them step on you.
You should defend yourself in an appropriate way sure, that your attacker isn't hurt is not a concern when you are being attacked. Which is pretty much what the MC did here, there was not to much force involved from him, if anything he was holding back.
And men like it if you use violence against them, unwarranted i might add ?
Respect is a two way street, i sure as hell don't respect someone which isn't respecting me.
If someone attacks me i sure as hell defend myself, woman or man really doesn't matter.
The problem here, is that you have a society that is segregated from males, none of those girls were exposed to males, all they know is that they are BAD, they will hurt them, they will not respect them. They aren't against the MC. They are against he's being male.
They are NOT in a equal environment, they are in a place of complete and utter imbalance. They were raised believing and knowing that males are this and that. When one is suddenly thrown to them, what would be expected? Do you know what her parents told them?
Yet, you want to treat them as enemies. Destroy them for having the gall to defend themselves against a presumptive invader that will destroy their society. Going about it gently, not allowing them to hurt you, but also doing the least damage possible is the ONLY way to make them see you as Human. Right now they see you as the proverbial boogeyman that most probably haunted their childhoods.
They are NOT the problem, they are a symptom. If you use too much force, you will validate their fears. If you don't defend yourself you will never be respected, but, if you go too far, if you don't do it with kindness and go above and beyond on making sure they are stopped, but not hurt, you will make all their assumptions against males, true.
This doesn't require martial proficiency, this requires empathy and strength of character. You can't make them respect you, because that assertiveness will hurt them, you have to coax them into acceptance that will later turn into respect.
Also, they are not attacking the MC, they are attacking the idea that they were raised with, that ALL males are bad. Defending yourself is OK, until you make them STOP. Not one yota further.
If you hurt one of them, you'll lose them. That doesn't mean they are right, it means you are in the wrong place, because YOU ARE. Going for acceptance is the ONLY way this doesn't end up badly.
Think it over.
Peace