From a comment given:

Although I am all against PC running amok, I can see one possible explanation that would make sense:

During the presentation, Wahlberg said something about personally carrying concealed weapons on campus--which could be a violation not only of University policy but also the law.

IF Wahlberg said something along those lines, then the professor would not only have a reason to call the police, but the police would also have a reason to investigate.

I am not saying that is what happened, just providing the one alternative that makes this NOT a "nutty professor acting like a liberal PC loon" story.