Not by much, if you want to get technical. It really gets into the rights of a corporate entity to establish it's own operating rules. As long as those rules do not violate federal or state guidelines (specifically civil rights and labor law), they get to hire who/what they want to.
I'm sure Clarett's lawyers will not use that; they'll probably go after a question of a "restraint of trade" offense, that will insist (much as in the Haywood case 30 years ago) that the NFL is curtailing his ability to earn as much money as he possibly could earn were he to enter the draft this coming year.
To which I hope the court replies "Then by all means, play for the Columbus Xtreme".