If college football team is allowed to unionize at a university and are then able to negotiate a salary for services that goes above the...

None that I can see.  The fact that someone doing the job you used to do is paid more than you were is not in any way improper.  The major league minimum salary today is probably twice what it was 20 years ago, and much more than it was before the players unionized.  Masahiro Tanaka makes $20 million a year, Nolan Ryan made about $1 million, Catfish Hunter made maybe $350,000, Dizzy Dean made probably $30,000, Walter Johnson (the best of all of them) probably made $3,000.  None of them has any right to more compensation just because their successors now make more than they did.