The NCAA and their members are suppose to self-report any and all possible infractions. It is not a court of law. If the coach suspects, and in this case he should, the player should not be playing. If the truth comes out the games may be forfeited and the other players lose what they have done. He could have just sat the 4 games and be done with it.
My point is that accusations alone should not bring sanctions, there must be reasonable proof whether you're talking about the law or NCAA rules.
Ohio State went through this a few years ago and Jim Tressel was dismissed over it. Free tattoos for memorabilia that was given to the players. (Apparently the recipients of rings and trophies don't really own them and they can't sell them.
Tressel could have saved his job and the schools one year sanction by reporting what he knew when he knew it. He tried to hide it and it bit him.
We had a top team the year the sanctions were enforced but the school was Bowl ineligible.
Tressel is the one who caused Michigan's current problems IMO. They had a recent string of victories against us until he got here and the tables turned. They've been scrambling ever since to get a coach that can make them win again.
Here in Ohio those national standings aren't important to us fans. It's important to the school and the conference for the revenue generated but the only thing that matters to many of us and to Michigan fans is to win that last regular season game.