i think youre forgetting the part where it says monster high is for kids... an autistic child seeing a character having their same manners is nice, but a character stating that they're autistic like its no big deal (and its not anyway lmao) is 100% better
autism is something you're born with not something you acquire randomly, so if two parents actually cared for their child they would notice their child behavior and they WOULD look further into it to know if something is wrong or not. meaning they'll know pretty soon.