Devil's advocate here...
I'm a parent, and one thing that we as parents experience all the time with our special children is judgement. My child melts down, he has a hard time not doing that in certain situations. It's not because he's a brat, it's because he's overstimulated for whatever reason and he can't help it...he's 8.
My son is direct. It's how he communicates. He doesn't understand semantics, rudeness he is just starting to get, etc. He's 8, and he's still learning social graces and will for a long time. He doesn't learn that naturally, he has to be taught and then he has to remember on top of that. He's not rude and selfish, he's missunderstood.
People look at my son through NT eyes, and pass NT judgements based on NT points of view. I'm not a bad mother, I don't let him get away with murder, I deal with inappropriate behavior, I accept the things that are hard for HIM that give him difficulty because of his neurology and I give him the time to learn in his own way and his own time.
I feel sometimes the same way as that man may have felt and I consciously try not to say, "my child has autism and he's not really beating up your kid, he's just trying to make him listen and he doesn't quite know how to do that yet". You get tired of people judging you and coming to the conclusion that you are a bad parent or your child is spoiled or whatever, and it's hard not to be compelled to explain. I am all about overcoming difficulties, but you can't expect every child with this challenge to overcome everything, and learn things at the same rate as NT kids. It just doesn't always happen. This goes for anyone with any challenge outside of the norm. People don't understand this and the judgement gets tiring. I have even gotten to the point that I can't even deal with talking parenting with anyone that does not have a special needs child. They just piss me off. I have a stepson with ADHD. He's not lazy, he tries his best, and he, by choice, tries without meds. He's not always successful. Get off his back.
Try not to judge these parents too harshly. I can't speak for this guy, but people may just be trying to protect their kids from the ignorant world out there.