We just rec'd a strong recommendation to get our 14 yo son into a fast track program at U of Washington. From a professor there who was his Nuclear Science merit badge counselor.
So we're thinking about it, though it sounds a bit different than what you describe. He's ready for his GED and then some, but in this state they want the kids to wait until they are 18 to take it. And we have to get permission from the school system for him to take it early. Gotta love it....
Check the actual law carefully. Here in PA, they can do it early if the college they're going into says it's academically required. There may be a way to work it early.
Also, if he were in a private school, would he need school district permission? If not, there may be a homeschool support group in your area which is organized as a private school, which you can simply "transfer" him to, and which can issue the needed permission