There is a massive difference between the needs of a G and T and and a child with SEN within a school.
From many years of experience of working with a wide range of children I can categorically state that the very bright simply don't need the level of support that the children at the other end of the scale need.
An example. I once taught a class with 4 children who were functionally illiterate. There was no way that there children could access the 'normal' curriculum. They could seldom 'be left' with instructions and left to get on with their work. the lacked the organisational skill, memory and reading ability to be left for more than a few minutes in a lesson. they needed a TA to give them constant support and guidance if they were to access anything of a lesson.
A child at the other end of the scale is massively easier to deal with within the classroom. Being able to read, having better memory skills, and a greater grasp of the topics, it is quite an easy job to keep them stimulated and on topic. In fact, being able to work on their own is often a defining characteristic of the bright child.
I have never yet met a child that I cannot stimulate within a lesson if they are able.
I have, sadly, lost count of children on the SEN register who I, and the rest of the educational system has failed.
The two are simply not comparable
Piffle, I terribly sorry about the situation you and ds find yourself in. Is CAMHS involved? {sends useless hug]