"her family worked the system to maximize her GPA, within the rules of the school district."
if someone abuses regulations and funds intended for disabled people while she is capable of a lot more than an average student, that is not "within rules".
That sounds suspiciously like the liberals who bleat about "fairness" instead of equality under the law. The Congress in its lack of wisdom passed the ADA. The school district set up a system to comply with the ADA. This girl and her father APPEAR to have studied the system, realized that there was a way to "win" that no one else had spotted, and used it. As she was approaching the finish line, the people who created the system in the first place realized what had happened and tried to yank away the prize. But you just can't do that. They should have written a system that couldn't be exploited so easily in the first place. Having failed to do that, the best thing they can do is follow through, give her the prize, and redesign the system so that the same thing won't happen in the future.
If there had been fraud or something of that sort, it would be different. The girl and her father could be sued, possibly even prosecuted. The fact that neither the school nor any of the other students appear to have even considered doing so tells us all we need to know: she followed the rules as written, and exploited some flaws she discovered in them. And her classmates are going to have to live with the consequences of the school district's incompetence.