There is never justification for violence.
And freedom of expression must be a basic rights for all.
But come on, offending delicate sensibilities of fellow humans is still a stupid, bad, unnecessary thing to do. Of course I "can" draw cartoons of the prophet Muhamed. But the fact that I "can" does not mean I should, or do. I "can" but I chose not to. Hurting others is never a good thing.
No....?