Words have an impact.
In the case of bullying it has led to multiple deaths. In the case of terrorist advocacy, it has led to repeated violent/racist protests that has led to countless people getting hurt and in some cases dying. No one should have the right to advocate violence against all members of an ethnic group. Just look at what's happening in France.
The thing is that not allowing people to speak their mind leads to everyone living in fear. Bullying will happen to some extent, and I think real life is way way more important than the internet.
There are also loads of things that are worth some deaths. I'm not saying that this is one, but the ability to live free of the government controlling every part of my life is one. A million kids having lots more fun, and one dying, is a good trade off in my opinion.
I think we're talking about different things.
You're talking about people being afraid to criticize their own government. I'm fine with protecting such criticism as Freedom of Speech.
But what happens once we reach the ignorance -> fear -> hate -> violence cycle? What happens if someone taps into people's ignorance by spreading literature that taps into someone's ignorance about an ethnic group, leads to fear, hate and eventually violence?
If we can prove that origin post was factually incorrect, it should be removed (not protected by Freedom of Speech) because it incites violence and is factually incorrect. If the person keeps on spreading this kind of hate speech then the person himself/herself should be penalized.
On a slightly related topic, we should have zero tolerance for online bullying. The sooner we out such posters (remove their anonymity) the sooner this will stop. Right now a lot of online bullying goes unpunished because it's too hard to track people down. If the children posting the malicious content were identifiable they would not do it.