Those before me have given some wonderful advice.
The college classes during high school are a great way to introduce them to college and how it works while still having high school to be a part of.
It is hard to finish those last months, especially after he's had a different life style. It probably feels to him like he is spinning his wheels.
Is he in line with the credits he needs to graduate in June/July?
My daughter did not go with the flow. It wasn't necessarily because she wanted to work it was just that it wasn't working for her. She did the 'Learning Center' {I think this might also help to catch up on missed credits for time when they've missed credits?} and then did indendant studies. She didn't get a GED but some other type of certificate. It is what worked for her, kept her going. She did go to work after and took a few classes at the community college. Now she is attending a school to get her nutritionist license.
I know you are worried about pushing him too hard in the direction you are choosing, in case it doesn't work and instead breaks him. Try the things people have suggested, keeping your mind/eyes open to him. He may take to it, hearing it from his counselor and others just might work. If you feel that it just isn't working, well, step back and see what needs changing.
It will work out. Just remember we felt this way before they walked, got out of diapers, off the bottle, wrote, read, and how many other things.
One thing I would suggest, {over anything else I may have said} don't listen to other people who might judge your son or you. Whatever you end up doing, that is right for you. Whatever choice you make is up to you.
I wish you luck, sincerely.