Sorry but I feel like yapping about this so..
I'd say you are trying to reason against a factual point made in the post. For that your fist step is to remove as much (social) context from the hypothetical as possible by referring to an abstract entity and opinion. And to be honest, your factual reasoning is impeccably, logically true. But are you sure anyone was having this debate with you in the first place? Not to discredit you, but your three step argument here is as succinct as it is obvious (at least to me). I disagree not with your argument, but your choice to engage with the original statement as a factual debate point. There's a chance the OP had intended to communicate a very different message than all men's opinions on oneself being always irrelevant. Removing context to only engage with the factual dimension of their statement deprives you of a chance to learn more about the OPs and the communities intentions and values. Much like past public conversations (remember gamer gate, or more recently the hypothetical of the bear vs man) I personally believe the point of hyperbolic feminist statements is not for you to debate them, or push back against them, but to understand them. After all, saying essentially "not all men" is factually true and very easy, but doesn't actually help anyone/improve anything. I wonder what kind of social interactions would lead to OP posting this (and this community identifying with it)? Perhaps a systemic patriarchy could put unjust pressure on a person to push them into a very understandably unnuanced response to such mistreatment. Either way I gain much more insight by empathizing with the post. Arguing factually would feel like punching ghosts while wasting energy that could be used to improve society a little.
I know that for me anyway, I read similar opinions when I was a young man and felt unfairly discriminated. But to be honest, looking back, I was never entitled to women who had suffered much worse under the patriarchy expertly lecturing me in my relative privilege (and all that without hurting my feelings). Like sure, me feeling unfairly judged for my gender whenever I misunderstood such a post as an attack on me personally was unfair too, but simply not the point, nor a priority here. If I could travel back in time to give some advice and emotional support to the young me, I'd rather find someone else who needs it way more to give it to. Nowadays I like to consider words not just for what they communicate, but also for what they do. And if this post helped someone vent who really needed it and gave a relatable outlet to this community than all I have to do is recognize it for the mutual support it is. I'm writing this because hearing it earlier would have saved me much frustration fighting imaginary misandrist feminists and because I'm also still just figuring much of this out myself.
Aww man, this is not the follow-up I was hoping for..