I remember when Oslo's mayor (iirc?) said something along the lines of "this is something a free society has to live with if it doesn't want to surrender their freedoms" after Breivik's attack.

We need more politicians like that. People who are capable of telling how it is: There is no sane way to prevent anyone from burning books. We can only invest in education and hope that people get the message that burning books doesn't do anything of value.