DePaul claimed they blocked Shapiro from speaking due to "security concerns"[0]. In particular, students in favor of safe spaces and trigger warnings threatened to riot, block the doors, and prevent student access to the event. DePaul capitulated to this bullying by banning Shapiro.
Related: California State University-Los Angeles planned on hosting Shapiro to speak, but demanded[1] the student group which invited him to pay $600 to the university in security fees. When the student group refused, the university blocked his speech.
I'm not aware of this happening to speakers holding majority political viewpoint; it affects the minority viewpoints primarily. Frame it in terms of race: imagine a modern campus saying, "We allow blacks to speak, but only if they pay hundreds of dollars to provide security against the white riots that will inevitably arise."
[0]: http://www.washingtontimes.com/news/2016/aug/1/ben-shapiro-b...