I can sympathize although I'm not sure how much help I'll be. Although our school district states right up front that twice exceptional children, underachieving gifted kids, and those who are showing behavioral challenges are to be included in the group they serve in GT programming, they go on to state that,
Quote
Gifted identification, however, does not guarantee specific GT services
and
Quote
An ALP [Advanced Learning Plan] does not mean that your student will automatically be in an advanced class.
and
Quote
...an advanced class might have different criteria than gifted identification. Because advanced classes have a faster pace and require a student to go deeper into the content, certain skills and characteristics (such as work habits, attendance, past performance, and motivation) are considered before enrollment in an advanced course.
I've long held that the programming is essentially "hard worker, high achiever" programming rather than gifted programming. They even state that an IQ test alone, regardless of how high, does not necessarily mean that the child is gifted. We could, for instance, have two fictional kids:

Child A gets a low advanced score on the state NCLB tests (achievement) and As in classes (performance) and a 50th percentile IQ score. He could be ided as gifted and tracked into advanced classes b/c he shows the requisite characteristics such as good work habits and performance.

Child B could have a 99.9th percentile composite IQ score and a defiant challenging attitude. With high achievement on state tests, he might get ided as gifted if the parent fights for it, but it is quite possible that he'll be excluded from GT/advanced classes b/c he doesn't show the required characteristics.

So, after my long complaint...

I've fought for a Child B b/c I have one of those. Mine is twice exceptional. Yours may not be (nothing you've said sounds like it thus far).

What I wound up having to do was:

Take my fight for identification to the district & got the policy changed on accepting IQ tests (previously they would only accept group tests like the CogAT). We gave them the results of multiple IQ tests with 99th+ scores on the subtests they accepted plus a full neuropsych eval. It sounds like you've gotten past that hurdle already or it wasn't a hurdle in your ds' instance.

Thankfully, like you, I have an older child who is the stereotypical recognized GT kid who is also grade accelerated. That bought me some credibility with the school GT coordinator. I met with her and dd's teacher and insisted on a change in the placement and was prepared to change to a different school if it didn't happen. My dd is not a behavior challenge, just 2e so they actually wanted to keep her at their school and the GT coordinator went ahead and moved her into the subject accelerated math class despite erratic performance.

The change in placement was a challenge initially b/c she hadn't been adequately challenged in math for years, but by the following year, her performance skyrocketed and she's done really well with continued acceleration.

Do you have anything you can hold over them (a different school you could change to, talking directly to the district regarding their policies, etc.)?