We (as outsider observers) lack the evidence to judge this story objectively. It sucks to be unfairly accused of plagiarism (it happened to me once in high school). However, we don't know why the professor came to the conclusion that she plagiarised. Maybe they jumped to conclusions on limited evidence, or maybe this paper was written with vocabulary and sentence structure which was inconsistent with the student's ea…
Your priors are naive. To be honest.