The fact that it demands violence off men. As my very next sentence states.
Demanding that a 'masculine man' is capable of violence is making men ... more violent. Men being too violent is a decently big societal problem. Hence, the idea that men should be able to defend themselves (and others) is harming society.
A man that can protect their family from a criminal or home intruder is harming society? Men with enough balls and sense of duty that join armed forces, so society is able to protect itself, are harming society?
If I was Putin or other adversary of the West, I would pour tons of money into promotion of this self-castrating idea.
They didn't say those things did they? They said "the idea that men should be able to defend themselves (and others) is harming society." The idea that they are duty-bound to these things by their manhood, not that they choose to do so. People should feel free to make their own reasoned choices.
I ging it sad and frankly creepy to think of the many great minds who have added so much to our society being sidelined or pushed down arbitrary funnels in their lives because someone had an obsessive idea that they needed to prove a biological tautology of "having balls" by going down a certain route towards militancy.
That's exactly what "they" said: "the idea that men should be able to defend themselves (and others) is harming society".
"Their" twisted logic is "man defends his family" -> "man gets more violent" -> "man gets too violent" -> "much violence is bad". I'm not sure if it's troll, stupidity or sincere and intentional self-castration.
Demanding that a 'masculine man' is capable of violence is making men ... more violent. Men being too violent is a decently big societal problem. Hence, the idea that men should be able to defend themselves (and others) is harming society.