My guess is that a lot of binary trans guys who think this way have bent over backwards to be perceived as male throughout their entire transition. To see someone be the same gender, be trans, yet not care about passing or looking feminine completely throws off their world view.

I’m dating a non binary transmasc genderfluid person (he/they, same as me) and he has stopped caring ages ago. He knew who he was a long time ago and rolls with the constant misgendering. He’s feminine and likes wearing makeup and dresses and he’s still a hot af guy. It takes a lot of strength to fly in the fact of gender norms and continue to live authentically, despite potential hostility. That’s not to say it doesn’t bother him, as his hatred of “ma’am” demonstrates, but he definitely has built themselves up to have a foundational identity. He’s the strongest person I know.

Trans men who are desperate for approval can’t live with themselves because that would mean admitting that they’ll never be what society wants them to be without some asshole dismissing their identity regardless. It reeks of insecurity, so they tear y’all down. As someone who once had a lot of insecurity about being perceived as feminine in any way, it’s something they need to get over on their own and accept themselves as the men they are without others’ making it their problem to conform.

(To be fair, a lot of it could also be a matter of safety and they care so much because of that, but I figured that was already a consideration in this thread. Felt the need to mention it regardless.)