I was thinking the same thing. I am by no means an expert but maybe some of his anxiety stems from not wanting to disappoint you.
I don't know the resources available in your area, but where I live there is a job center where special needs kids ( in varying degree of capability) can work for the summer. It is very well received and these kids get a great sense of accomplishment and make a few bucks.
Maybe he would be interested in spending his summer that way as opposed to more schooling and I think the benefits to him would be huge.
Just my 2 cents.