This seems to be the main argument from the University of Calgary in their decision to disallow the public display Scott discussed here. Here is a portion of their letter that they sent to the organizers:
Of course, the violence that the pro-lifers warned about is the violence that could be perpetrated upon them. They are informing the school that a small amount of security would help to decrease the chance of any attacks upon them. The school's response is cowardly and pretty amazing - in order to be safe they cannot let any "discussion" comparing abortion with the holocaust and the Rwandan genocide.
Imagine a group that wished to protest against campus rape. They had images and were prepared to discuss comparisons of rape with the issues of other violence and other forms of past abuse of women. They were concerned that a small minority of the men who viewed these images and discussion could be upset enough to attack them - despite the fact that there were no attacks during the other five times that the signs were displayed.
Would the woman's group be made to hide their signs and limit discussion of the issue in the name of safety? Would they accept that?
Living life without being confronted with points in which you disagree is not a basic human right. A college campus is the perfect venue to explore the more controversial issues that confront us. This craven attempt to protect the students from a viewpoint that they may disagree with is morally vacuous, and unworthy of a higher learning institution of any form.