If I were you I would have him give the local school a try this year. No school decision is set in stone, he can make a different decision again when time comes for HS if he wants to. But getting rid of that commute AND moving on from a program that maybe isn't at "GT" as they advertise is probably a good idea in spite of what others may think about the move. Use the commute as the excuse (since it is legitimate!). I suspect he is just getting cold feet regarding the social side of starting over again. Who wouldn't?

Here are a few thoughts:
- Look for activities in his middle school that are academically oriented that he can get involved with. Aligned with his interested, of course. Like chess club, math club, science club, writing club, etc. When he gets to high school, there are usually more (debate, school newspaper, quiz bowl/various academic competitions). My D has "found her tribe" in those types of clubs at her school.
- Make sure he stays on the academic track for any AP or accelerated options that do exist at the high school. Algebra in 7th grade is a good example. But take a look at the high school curriculum and find out about any pre-requisites for the more advanced classes.
- Does your state have any option for high school kids to take college classes? Our state covers the expense for college courses starting junior year for qualified high school students. BUT, it can be hard to get into the program at the state flagship (which is in our town), so figuring out ahead of time what the options are and what is required is a good idea.
- If you can, supplement academically in the summer. Might be a challenge with 5 kids due to cost... but my D had some great summer academic experiences taking classes, collecting insects for 4H, and attending Davidson THINK. She is taking a free online statistics class through Coursera this summer on top of other activities, and enjoying that, so look into those for him as well. For my D, she needs to be learning new stuff all the time or she is unhappy. So we look for a lot of ways to feed that beast.

Good luck!