To clarify: the entitlement is not to gifted and talented services as such, unless your particular state has such an entitlement on their books - IDEA and 504 are pretty much silent on the topic of giftedness. The 504 and ADA entitlement is an entitlement to the same access to educational programs that would be offered to similar students who did not have disabilities (so, for example, a dyslexic student can not be barred from a gifted program that would be offered to non-dyslexic students with the same ability levels, and the school would have to provide reasonable accommodations to allow the dyslexic student to participate) and the IDEA entitlement is to a FAPE (free and appropriate public education) for students with disabilities which affect their educational performance. A FAPE is defined as one that the student can derive educational benefit from, so there is an argument to be made that acceleration is necessary part of a FAPE for a student with a disability that affects educational performance who has mastered all grade-level content.
