Truth is heavily subjective. Some people think the truth is that all of Islam is responsible for terrorism, and therefore could encourage unjust violence/stigmatisation (even more than that which already exists) for muslims. Of course, this is not the truth, as terrorists come in many forms, but with completely free speech the jeopardy of the people's safety is infinitely possible.
I do however agree that we need to make some modern world progress, though not through letting anyone say anything. You have to filter out the impurities to make gold.