@MWolf: Those who invited the speaker to campus do not control the speaker or his words. The speaker is an independent contractor, not an agent of the person or group who invited the speaker to campus.
What constitutes harassment or inciting others to riot can be and is very different in the US than in an area of the world where acts of terrorism are quite common & where there is a perpetual state of war.
P.S. I also ask you to consider the effect of inviting a controversial speaker to campus who might address potentially incendiary issues. For example, this can be a tactic for creating unity by those close to the issue or issues.