Children with disorders or syndromes that affect their behavior are especially challenging. There are often not enough staff members to provide these children with the discipline and attention they need to avoid distractions and acting out behavior. Couple that with the fact that autism/aspergers is still a relatively new disorder that is still being investigated and evaluated, and you have a triple whammy.
Before jumping to conclusions here we need more information. Did the parent discuss the methods that the school would/could utilize to handle the child during the IEP sessions? Was this method listed as an option on the IEP program? Did the parent inquire as to what methods might be used at any point in time? Was this a random decision on the part of the teacher, made with no knowledge of the use of a restraint device or "therapy bag"? Did the method work without traumatizing the child?
I've been in SE classrooms, I've been integrated classrooms, I've spent a LOT of time talking to SE/integration teachers. I've observed the challenges these teachers and assistants face, and I've seen first hand how little support the teachers/staff receive from parents of these children. In one class geared towards 3-5 year olds, many of the SE children were not potty trained. Parents would drop their children off in regular underwear with no change of clothes and no pull-ups/diapers, only to come in RAGING at the end of the day when the child was picked up wearing a school-provided diaper and no bottoms. I saw parents drop of children with feeding tubes that were partially detached or dirty, I saw parents pick up their children and completely ignore them. I saw a lot of good, too, but I think attacking the entire SE system is ridiculous. They're fighting an uphill battle with no reinforcements.