I agree 100%. Expression should not be limited. The issue I have with this is that the participants aren't expressing themselves. They're expressing someone else, "huh-huh... that's funny. I'm going to do that too."
And just to put it out there; I have no problem with you (I don't know you) and I am not trying to argue directly with you. Your's was just the reply link I clicked.
As for the cartoon, it was likely a mistake to give in to the threats, as it simply validates them and invites more.