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.
Originally, the idea of a law was to set a general proscription, and whose individual application would be checked by the proper authority (judge or jury) to see if it was appropriate. In this system, the just result was paramount. This is the legal tradition that our own system was built upon.
It is the left which believed governments could, through careful design, craft laws in such detail that every possible permutation could be predicted (As Oliver Wendell Holmes reminded, "Hard cases make bad law."). Under the influence of the left, law became about following the process as opposed to a just resolution.
To a leftist, the Hornstines were perfectly justified in "gaming the game," as that is all the law is seen as. This is the same mentality that has the court throw out a confession because the accused hadn't had his Miranda warning read word-for-word, or which sports twice as much time in evidentiary hearings as is spent on an actual trial, trying to get the evidence thrown out. I'm sorry to see that you have bought in to this fallacy.
I reject your assertion that violating the spirit of the law cannot be punished just as severely as violating the letter of it. To do otherwise is to Clintonize...