results of an achievement test called MAPS where he also did not score highly enough
This got my attention. When I asked about gifted services for DD6, I was told she didn't test high enough on the MAP test. When I looked into it further, it turned out they'd renormed her scores using preliminary data that I was later told shouldn't have been used. When the correct data showed she was clearly in the gifted range, I was told MAP was not designed to determine placement in any sort of school program.
If they're using his 3rd grade scores, the preliminary norms shouldn't be a factor since they were for K and 1st.
I'd ask specifically for a copy of his NWEA Student Progress Report. This has lots of good information including RIT score, Student %ile range, student growth and typical growth. It will also break down his scores by reading, math and language use. This may give you information to help with math acceleration. Here's an example:
http://www.usd320.com/Map_Site/progress.pdf