As the other replies to you go plus:
... "Freedom Of Speech" merely means the government will not put judicial sanctions on the exercise of speech. As owner or employer, the government can limit speech as much any private individual can limit speech. Federal civil service employees are restricted in their political speech as a condition of their employment. This is utterly and absolutely constitutional.
Expelling a student from a public university for not obeying a code of conduct isn't putting any unconstitutional restriction on freedom of speech since it isn't a judicial sanction. Again, the government puts all sorts of non-judicial limits on speech.
I agree that about the public accommodation part but that's a different issue - that's the issue of whether non-students will allowed to speak in semi-public places like Sproul Plaza. I think they should but I realize there's no constitutional basis for this.
Your unlimited freedom position seems to be asking whether a student should be able to shout "honky" or "niger" out their dorm window without being expelled from the university. I think they shouldn't be able to, they should be expelled. I think the university should have the authority to remove those who create an unpleasant environment and I think it should use it in a limited, appropriate way.
Of course universities should have codes of conduct, some part of those codes are going demand minimally respectful behavior. I boggles my mind that so many people want to grand-stand "freedom of speech" and "the constitution" only and specifically with regard to the "anti-PC" hobby-house.