A few things to note:
1. This person contacted the textbook company and apologized, admitting his true status as a student, before the company even sent him anything. Therefore, he hasn't unrightfully "taken" anything.
2. The textbook company has forgiven him and wished him luck in any proceedings.
3. He has already spoken with a committee member and expulsion is likely not an option.
4. This student sincerely accepts that he made a mistake and admits to not really realizing that he was committing fraud at the time when he submit the request. He only recognized the ethical considerations of exploiting the company's policy, for which he later apologized and "turned himself in" to the company. (Though it is important to note that the company already knew he wasn't a professor because they had contacted the university.)
Lastly, please try to give some constructive advice. I'm trying to defend this person, and I already know how difficult the task will be.