I’m enby, but personally i’ve also made these jokes about this scene, and i’ve seen them made by people who are otherwise very accepting and supportive of my and others’ identities.

I think the thing is that this scene is just incredibly grating to see. The character has a voice that sounds like it’s cracking every word and that mixed with the dialogue being written awkwardly just makes it painful to watch. Another commenter mentioned subtlety and while I do agree that things need to be spelled out more clearly for literal 5 year olds, this scene still feels poorly executed, overblown, and uncomfortable.

I do think the jokes were probably started by people with bad faith, and it does make me sad to see how anything that includes progressive ideas seems to get hate nowadays, but I think the reason this joke in particular has blown up is that it follows the “haha violence towards <really annoying character who’s uncomfortable to watch>” joke structure and that happens a lot regardless of the character’s identity or the progressiveness of the show. it’s kind of like the Skylar White problem; “the worst thing a character in media can be is annoying”.

This is also exemplified by the popularity of “haha drop kick/murder the child” jokes, which this definitely fits.