Personally, I would never hold a child back. It could potentially make things worse. It did for me. The child may see it as a punishment or personal failure. The child may be targeted and/or looked down on by classmates. It can really take a hit on ones self esteem.
The school should be working with your son. The school should change the environment to meet his needs.
Does he qualify for MENSA? The members may be a good support system for the family.