And yes, it does happen to the best of students. But at least you didn't jump around on tables and counters hooting like a monkey while the fire burned. This kid really was a troubled child.
You have put your finger on the problem with not being able to segregate special needs students without knowing it. You say that you would sue the district if they pushed your child into inappropriate classes. And sometimes, the parents are not being realistic about their expectations. Many parents are of the opinion that their child will do better in mainstreamed classrooms, and I do think that classes like art or phys ed or some of the other classes that are not academic (you know, the classes that all the schools are cutting) are probably good places for these children to be integrated in with other students.
But when I taught, I will say that these poor children with a lot of special needs were lost in regular classrooms....and if they are lost enough, they will often become discipline problems. What do they have to lose? They have no idea what you are talking about. In my science classes, some didn't understand ten words in the whole period. And I could not teach to them, or every other student would be bored stiff. Sadly, the way we are teaching at this point in time is to the middle....average. The slower students get lost, the advanced students get bored.
I was classified in a tracking system as just above special education classes. I was pushed into "office technology" classes instead of the college prep classes. I had a long way to go when I did go to college for biology and general science education....I had never even had an algebra or literature class. Or a biology class. But I graduated college cum laude. So I know how much tracking sucks. But we have not come up with a better system yet.