Just saying because nearly every person I know who has ADHD and/or Autism (including myself) seems to care less about people knowing they're into "childish" things.
Also the idea that this is a new phenomenon because Millenials and older gen Z are "soft" or stunted in some way.
I mean, boomers have model trains and and cars. So did their parents. My grandma used to knit herself plushies. This isn't new. You don't suddenly stop having your old likes because you reach a certain age.
disney adult and nintendo adult seem way more specific than manchild, like i'm pretty sure a bunch of the disney freaks are perfectly neurotypical.
manchildren are probably a mix of people who didn't get care (and deserve some accommodation if we're not definitionally excluding non-harmful behavior) and "weaponized incompetence" types who could simply make better choices.