Not to take anything away from a 3.5 GPA, but there's a world of difference between being able to perform in an academic environment and the high stress situations you may find yourself in while in the CG. If you're on meds for your ADHD, this is another issue. You wouldn't want to be on an hours long SAR (search and rescue) mission, only to have your medication wear off, or on a 90 day patrol, only to find out you only have 60 days worth of meds.
My son was diagnosed with ADHD at 8 years old. He's now a college sophomore, studying computer science. We had a 504 in place for him in high school, but he chose not to use it. In my opinion the 504 is a double edged sword. While it's helpful in the academic world, it's not practical or realistic in the real world. That's especially true in the military