Schools vary so widely that I would not assume that the school he is enrolling in is ONLY for low functioning kids. I also don't agree that gen ed is always the best option. It depends on so, so many factors.
Middle school is an absolute nightmare for kids with sensory issues, social issues, behavior issues etc. This is the age with many families with money withdraw their children from public school and put them into private schools that are smaller, more flexible, or provide specific support for kids with special needs. I believe it is absolutely appropriate for public school system to provide options where kids can be successful.
There is a massive difference between being able to do the same academic work as other kids your age, and being able to get through a day with bells ringing constantly, lockers slamming, every teacher having a different set of rules, every teacher interpreting your IEP differently, the teachers for specials having NO training in special ed, etc.
"Least restrictive environment" is just an excuse many school systems use to NOT meet the complex needs of kids who are neurology different.
My DD became a high school drop out at 16 because there isn't a single high school in our entire city -- public or private -- that can meet her needs because she is on the spectrum with sensory issues that are off the charts and an anxiety disorder, but is really smart in areas other than math. She is now going to community college, which is working out well for her, but everything that it takes to make it possible is only possible because we have money and education. If we didn't, she really wouldn't have an future because *she cannot attend a traditional school*. Gen Ed isn't doable for her; she can't even make herself walk through the door. Special ed isn't an option because it isn't the "least restrictive environment."
DaisyO -- I hope the school works out well for him. I know a lot of wonderful people working in special ed and I hope that he will now have access to teachers and other professional who can really reach him and help him find out how HE can be successful. Also, the book "quirky kids" by Klass has information on non-verbal learning disability and other closely related disorders. It's a good starting place.