Sesame Street is a very left-wing Children's franchise, much like the Muppets. Not surprised they did this. Big Bang Theory did this themselves with Sheldon in a way, but they were smart to make sure it never mentioned that he actually had mental disorders. I'm concerned that if Sesame Street outright says that this "Julia" character has autism, and they show her acting a certain way in the show, it might just reinforce bad stereotypes about autistic kids. It'd be better if they had her just act quirky and simply not mention whether she has some sort of mental disorder or not. If they start putting labels on children's characters it might mislead kids to think that all characters with autism must act like Julia will. Which is not the case because autism manifests itself in a huge variety of ways. No two people with autism are the same.