This argument doesn't work, because if you "shut it down" you show you're an incredibly selfish person. And if you show you're an incredibly selfish care-about-me-more-than-winning person, then your draft stock will plummet. No one will want to spend their first pick on someone considered a diva.
He's already proven that he's a winner. It's not "incredibly selfish" to make a decision in your financial best interest. Especially when the college game is so clearly exploitative.
Running backs only have a limited number of hits/years in them.
This guy argues that you can expect 8 years out of a quality running back, but I'd argue that most start to slow after 5 years or so in the NFL. By avoiding a whole season of college ball, he can not only extend his expected shelf-life by a year, he can gain a significant physical advantage on the guys who spend the year playing.
Just look at what happened to the Irish this year. CFB wears you down. Once you get into the season, you stop lifting to develop and you just try to not lose gains. If he didn't have to worry about playing for a year, he could physically outclass any other running back in his peer group.
This x100. What if he tears it up his first 3 years in the NFL? Think he should sit out his 4th year so he doesn't get hurt in the last year of his rookie contract?*
The difference, of course, being that he would be paid millions of dollars to be in the NFL vs. having a scholarship to a school that he doesn't plan on graduating from in CFB.
I get that it would be a bad look. Maybe he should smoke some pot before a drug test or deliberately get caught cheating on a test. For some reason, people would be able to stomach that better than they would him coming out and saying no matter how much I love my teammates and the program, I cannot risk my future by playing another year of football. I have an incredibly valuable skill set, but I need to maximize the financial returns I get from that skill set because I understand the league will discard me the second I lose my edge.
And his teammates, they might not love it, but they all won a NC because of him, so it's tough to imagine them complaining too much.
*that being said, the NFL would probably be able to put together a better product if they expanded their roster size by 33% and mandated that every player (maybe every non-QB) take one year out of every three off.