Any school and athletic department should have standard code of conduct for scholarship athletes. By default, most should look similar. IMO, if you are representing a school publicly in any forum, be it football, basketball, chess club, bowling, or whatever, there should be an expectation from the school, and the respect of the individual for that school to represent them in a professional manner while attending said school on scholarship, athletic or academic. People do make mistakes, and a lot of them can be worked through for the good of the student and the school. But, there should be common ground on when a student/athlete has worn out their welcome.
I think that applies to a lot of this nonsense about not standing for the national anthem. That is not the forum to profess your political views and protests. You may be a "pro athlete", but on Sunday's you are on the job representing your company. Period. And for the crappy fans that dishonor the anthem while it is playing, but want to criticize players for protesting, go suck the same egg. Wrong thread and forum. Sorry, but related ideals.