The school can't punish a student (the alleged rapist) without evidence; it is, however, obligated to provide a safe and comfortable environment to the victim. Assuming the girl wasn't requesting an opportunity to actually publicly shame her attacker at ballgames, a sympathetic cheer coach could have found a compromise rather than kicking her off the squad outright.
There are people to appeal to all up through the school system before resorting to legal action; I don't know the details of the story but I'm curious whether she and her family exhausted those options first. This being Texas, it's entirely possible they complained all the way up the chain and still received no support; in that case I can certainly see some ethical justification for going to court, even if I can also see why the judge found in the school's favor.
Without further information, it's generally a safe assumption that a party will have exhausted non-judicial, administrative remedies before going through the stressful and absurdly expensive process of suing the government.
That being said, even if this girl and her family went straight to the courts because seriously, what the fuck, suing somebody because getting treated like a subhuman really, really pisses you off isn't by itself grounds for sanctions.
