Yeah I am not only talking about trans people though. Cis men can struggle with their masculinity too. And I would give you the "they mean the toxic men with crazy requirements to others" but when we claim that we are about making people feel comfortable and included, which at least I do. Then we need to ask ourselves if there is inclusive language that you should use, is there exclusive language that we shouldn't use. What is exclusive language? And the answer is e.g. saying that a man that struggles with manliness is not a man. Sure, the suffering of trans men are worse than e.g. a cis man that doesn't feel manly, but we shouldn't play the victim Olympics but support each other in our struggles. And a blanket statement that ridiculous men who want to feel manly, is just toxic language. Generalization is the issue. I am firmly in support of people who struggle with gender or ethnicity or anything similar. We are brothers and sisters and I don't like them bullied. I want them comfortable.
If you would be upset over someone making fun of a trans man's struggle of feeling like man, maybe don't make fun of a cis man.
If you aren't upset over someone making fun of a trans man's struggle of feeling like a man, you are an asshole.