To me, this looks like the "get the data" stage.
If I'm reading this correctly, your DS7 was accelerated three years in math last year. Assuming he was six, and enrolled in the age-appropriate grade, he was a 1st grader doing 4th-grade math last year. Is that correct?
If so, that establishes his level = 5th grade math. I'd start examining his math work, and comparing it to your district's grade level expectations for 5th grade math. This data would inform your next step. Assuming it's not a match, you can present this data to your principal as evidence that his group is not, in fact, working at his level.
