This is some ass-backwards "Don't start nothin, won't be nothin" logic. Drawing cartoons is not the act that is disturbing the peace. The small percentage minority radical Islams that kill over the cartoons is what is disturbing the peace. Deciding that the correct action to take to this is to treat drawing those cartoons as an act that is disturbing the peace is literally what terrorists want.Free speech is an absolutely wonderful concept and for the most part, it's used appropriately and with good intentions.
Unfortunately, people like these bikers and the Westboro Baptist Church completely abuse the intention behind it. They are both inciting violence and once that happens, their right to speak freely in that manner should be quashed. Disperse them and send them on their way.
No right, no matter how important, should be limited when it infringes upon other people's right to live peacefully.