I hate to call Nick stupid, but this is stupid. A salary cap can only work in a league with athletes as employees so that there is collective bargaining between the league and the players. College athletes aren't employees of their schools or leagues, and never will be. Their college careers are too short for one thing. For another, the schools don't want to give every college athlete all the benefits that employees receive; insurance, pension funds, etc..
And even in salary cap leagues, there is no cap on endorsements, hence why athletes prefer playing in big markets over small.
Nick has either; (a) not thought out his stupid statements, (b) is too stupid to understand the legal issues (unlikely since he coached in the NFL), or (3) is just talking out of his *** because he is losing at recruiting in the NIL world. I will go with (c). Nick is not stupid but he is very, very frustrated that he no longer controls his own world.