It can be difficult to see and hear things that challenge your personal beliefs and offend the things you cherish. Academic freedom and freedom of speech mean that critics cannot silence that with which they disagree — however strongly they may disagree.
Individuals, alone or as part of a group, have the right to respond to a controversial speaker with protected speech of their own. This includes, but is not limited to, talking, circulating literature, displaying signs, and singing. However, they may not threaten a speaker or commit any violent act against a speaker. They also cannot participate in the creation of a situation in which the speaker cannot be heard.
Perhaps the best way to show disagreement with a controversial speakers message is to simply ignore them, denying the attention they are often seeking.