You said "his side of the story" like it was just his word and nothing else. When the truth is they investigated fully and found the story (his, hers and everyone else's) to be that she lied about her age in order to have sex consensual with college guys.
I don't think her original motive was to get them into legal trouble and I doubt any of them knew she was 17. It was basically kids looking to hook up. Then she went and fabricated at least Araiza's part in the whole thing, likely because she got caught by her parents and Araiza was an NFL prospect and had deep pockets when they went public since he had just made the team.
And if she had been 15 or 16 and still did what she did, no, she still shouldn't be protected. Again being young shouldn't excuse you from the consequences of your bad decisions. The only thing I'll say is that if she had been 15 or 16 years old, I think it would be easier to spot. But if you say you can tell the difference between a 17 year old and an 18 year old, especially at a college party where they're saying they're 18, you're lying.