And how are his rights being violated by being denied a job that he's not qualified for? The rules are the rules. If they let him play then they also have to let 20 year olds be elected president. Same deal. He's not old enough (mature) yet for that game.
(Recognize that not all Calvinists will be Christians in glory.
And there's absolutely nothing they can do about it either according to Calvinist thought)
If no team wants to hire him, and there is no collusion involved, he wouldn't be qualified. In that case the NFL argument is moot. I say let the marketplace decide.