Then the parents need to control their special needs children better. Any compassion that I may have ends when your special needs child lays hands (or any other part of their body) on my child.
I can understand you may feel this way. To have a better understanding of what these special needs kids and adults deal with as well as their parents on a minute by minute basis I would visit a local organization who have activities with the special people to help give you a more caring perspective for all involved. And I say this in the nicest most compassionate way.