I believe the First Amendment protects objectionable speech, subject to the limitations of things like false and defamatory speech, and speech which is an clear and present incitement to criminal acts. In the latter context, "Death to Israel" is protected speech, but "Allah demands that you go out and kill Jews" is not.
What about if Muslims in a student organization event start singing a song about throwing Jews in the gas chamber?
Could a public university expel those students?