At fairly regular intervals my grand-daughters complain that the "special needs" kids are disruptive and make the class an exercise in futility.
My sympathy in these cases are with the teachers who have their classes disrupted.
I have a close friend who has been a special-ed teacher all her life. I think she might agree with me that too often parents of special-ed kids demand that their children be "mainstreamed" without regard for the other kids in the mainstream classes.
I stand here (actually sit) to say that kids can be taught all the fundamental skills of social behavior without having to be put in regular classes to be disruptive. I've known some parents of special-ed kids who were superb at teaching their kids manners.
By manners I mean all the classic manners: never interrupt another person when they are talking; say please and thank you all the time, listen to and look at other people in the eye when they are talking; adjust your voice to the circumstances; etc.. you know the drill. Most six year olds can learn these lessons.
Social manners should be fully ingrained before "mainstreaming".