The protesters shouted questions at her and then didn't allow her to answer. Other students, who wished to inform themselves about Gore's environmental policies, were unable to do so because the speech had to be aborted. So some folks think they know all there is to know about the issue, and don't need to hear the other side. Okay, that's fine. In that case, dialogue could help them convince others of their points of view.
Dialogue is one of the best methods of persuasion.
And if protesters are so sure of themselves, there's nothing to be afraid of. It's extremely important to challenge people like McGinty. We would have loved to hear objections to McGinty's speech, and we would have loved for her to hear them, too. But she couldn't hear them because they were being shouted at her from all directions. It's easy to shout when no one can respond.