I 100% agree with this. He's already behaving badly, and overall it's a huge red flag of a comment.

But his male friends are presumably his friends from either prior to the relationship or with no regards to his partner. They would be betraying a friend they're fond of to act on this attraction.

Her male friends do not care about hurting his feelings anywhere near as much, and may even have delusions of replacing him. Many of them may have become her friends directly because of their attraction to her.

I don't believe that this inherent means that he intends to cheat on his partner with a female friends of his own, and therefore believes men are like this, to be clear. I am lucky enough to have a beautiful partner, and have close female friend who I have platonic friendships with while aware those women are very attractive. But I wholeheartedly trust myself not to act on any attraction to anyone else, which is the bare minimum of course. There are men my partner is friends with who I can tell are attracted to her, but largely I don't care, because I wholeheartedly trust her to rebuff them too. But I'd also expect that if one of them made a move on her, she would distance herself from them.

To me, his comment means "I don't trust you around people who find you attractive." That means one of two things. Either he is behaving possessively and exerting authority over her, or there actually is basis in his comment. I'd assume the former, largely because personally, I've known more possessive men than women who would cheat but we don't really know enough about the situation.

Overall I hate the entire post and absolutely do not believe these two people are going to have a happy relationship.

Edit: I support her in maintaining those friendships. If he truly believes she's not trustworthy to be around those friends, and does not want to remain in a relationship if something were to happen there, he should leave her. If it's in his head and he's behaving possessively, she's better for it anyway.