cantfind I wish we didn't have to engage with the state so intensely, but needs must.
The provision is solely driven by DCs needs, and it is about helping them to meet learning goals. DS is a bit atypical, as he is achieving fine academically, but his unpredictable aggressive outbursts mean that the 1:1 is first and foremost there to help him manage his behaviour to keep him and the other DCs safe. If he withdrew into himself instead, I would not expect that he would get the same level of support.
Have you tried consulting with an educational psychologist, who sees children in both state and private settings, to get an independent perspective on what your DS needs? I think what all parents are looking for is some reassurance that we are doing the best thing for our DCs, and when you find out your DC has ASD, your standard route map just got torn up.
My rule of thumb, fwiw, is that DS is (now) happy and making progress. He seems to be academically bright, however his ASD may mean that he cannot fulfil all of that potential. As long as he is happy and progresses to live independently, I won't lose too much sleep over that personally. I know that wouldn't be the right approach for every parent.
If state school stops working so well for DS, we will not hesitate to look at the private options, hence finding this thread helpful.