In 6th grade, the most popular way for bullies at my school to insult other students (and one another) was to say, “You’re special… SPECIAL ED!”
Then they would run off, cackling at the cleverness of their wordplay. If a teacher heard them, they might get a reprimand, but not for the right reasons.
See, teachers knew the bullies were being unkind, but they misunderstood who the victims were. They didn’t want students to hurt one another, but they forgot that it also hurts disabled people when disability is used as an insult.
Since I want to focus on the problem of disability-as-insult, apart from additional issues with the term “special education,” let me use “autistic” as an example instead.
I’ve heard “autistic” used as an insult, but that only makes sense if neurotypicals are better than autistics.
Calling someone autistic may be true, or it may be false, but in neither case is it a valid insult – except to the people whose identity has been borrowed.