The Bill of Rights is between the federal government and the people not the University of Oklahoma and the people. There are no freedom of speech rights held by students.
Do you really believe that the bill of rights doesn't apply to state governments? This is a position held mostly by Paultard weirdos and Confederate revanchists.
I wasn't referring to federal government to mean the national government, but the strict sense of the word. State and local governments are part of the federal system.
OK, but the University of Oklahoma is an institution of the state government.
Okay, but the government is still doing nothing to infringe the rights of the students speech.
These individuals can still go to the campus today and chant no n-----s in SAE all day long as non-students. Their rights to free speech are not infringed. They aren't going to jail. They aren't losing any property. They are losing their title as a student at Oklahoma and a member of SAE fraternity. There is no 1st amendment right to have membership to an organization against the will of the organization, even a public organization. If that were the case, I'd go demand the government give an Endowment for the Arts right now.
Of course there can be other qualifications required. The question is whether, when those other qualifications are met, the government can deny a benefit just because of the recipient's speech that does not pertain to those qualifications. The government can require that you pass a driving test and a written test to get a driver's license, but it can't require that you pass a driving test and a written test and write zero articles critical of the current government to get a driver's license.