The unfortunate reality of it is, is that you can be expelled for causing a disruption on campus. You cannot depend on the school to do the right thing. A student can be accused of a disruption, say either taking place in class or on campus. A professor, for example, can just disagree with the student's views in a class discussion and it could lead to disciplinary charges. It does, of course, depend on the specific circumstances at hand in terms of what that actual disruption was. Is it a student's right to academic freedom or discourse regarding a matter, or is it an actual disciplinary violation, which would include, say prohibited conduct?
It is case and fact-specific, but you cannot depend on the school to naturally be looking out for your rights or interests. Before you engage with the school in any capacity because of what's at stake, you need to have an experienced attorney advisor in your corner that can help best protect your rights and interests, and they can help you understand and navigate the process.