The reason I know that is because UCLA had a national televised game on Labor Day weekend a few years ago and the TV analysts said that students don't come back from quarter break until the third or last week in September.

I don't know when UCLA's athletic teams practice. It is possible that practice time conflicts with the start time of certain classes which means players have to decide which is more important; playing a sport on an athletic scholarship or attending class on your own dime. It is possible that some classes may only be offered in certain quarters. If that is the case, then he may never be able to take a class that he wants to take because it conflicts with football.