Hey, MON, I forget which state you are in. I think that the answers to your questions lie in the state special education laws and whether gifted is recognized as having special needs. In terms of the IDEA, it doesn't sound like the issue meets requirements from my understanding of the law. But if your state recognizes gifted within the special education laws, then you have a better chance of advocacy.

Under special education laws, the schools are not required to ensure that all children are working up to their potential or at their level of ability. They just have to show that the child is getting a "free and appropriate public education" (fondly referred to as FAPE) in the "least restrictive environment" (LRE) possible. I'm not up on the most recent changes to IDEA so I'm not sure if they've changed that wording or not.

But, as far as I can tell, if the dysgraphia and written expression disorder are not currently interferring with any of his academic performance then you are likely to have a hard time convincing the school to provide services. Have you considered a special education advocate? Or checked to see if your state offers any free legal counsel for special education needs? I always suggest finding the Center for Independent Living that serves your area and see if they have a youth advocate or resources regarding special education laws in your state. You can find that here:
http://www.ilru.org/html/publications/directory/index.html

I hope that helps. And best of luck with advocacy. I'm not saying he doesn't need help, BTW, just that advocacy using the special ed laws might be hard. I still strongly urge you to keep on advocating!!!