They were ceding to police and prosecutors the power to put people in prison for expressing their ideas. Each audience hears a message that promotes genocide. Were censorship of the offensive permitted, each audience would have an equal claim to be protected by police from that discomfort. But you can' t have it both ways. Either you embrace a free society and tolerate objectionable song lyrics, bomb recipes, racially offensive remarks and nude photos, or you enact laws against offensive materials and invite the routine arrest of writers, artists, photographers, philosophers, musicians, scientists and professors.
Freedom of speech is about power.
The First Amendment gives it to us, but, sadly as the poll results suggest, we believe it' s too much freedom for us to handle.