I bet the kid didn't frighten him and they lied. It looks more like the guy was on the phone and the kid was making noise and it pissed him off. He looked annoyed, not frightened. My uncle has Downs' Syndrome and people with disabilities tend to get frustrated easily by people not following rules and norms. If my uncle ever did anything like that we'd be mortified and he'd be in huge shit.

Just because people have disabilities doesn't mean they don't have their own personalities and quirks. It seems like this guy has a very poor attitude, and even though I wouldn't say he should have gotten punched, I still think he doesn't get a free pass and got what he deserved as a human being. Sometimes people with disabilities develop poor social skills and become spoiled from people treating them different than everyone else, so maybe he learned a lesson. They aren't dumb and they know what they should and shouldn't do. He may have the mind of a child, but I wouldn't even go as far as to say children are dumb, they just need guidance in some aspects of life. The biggest problem is that they just don't communicate well with most of society.

Also, he probably has a history of being violent so his mom or worker should have been watching him, or just shouldn't have taken him out. She is a lot to blame here.