Just a note on free speech itself: The right of free speech is a protection against the government controlling what you can or cannot say. That has never meant that anyone can say what they want, when and where they choose, and everyone else must respectfully allow them to.
Besides speech-related laws such as libel, slander, hate-speech, inciting riot, there are all the ordinary criminal punishments if speech provokes disturbance, assault, or some other crime. Nor is there any specific offence to punish someone who just disagrees, or dislikes what you said and tries to interfere with you or stop you from saying it. For that you'd have to rely on assault charges and other such stuff. Either way, if you're a cop you can't do very much until someone has already done something that's against the law.
It's easy to sit at our keyboards and criticize. Imagine yourself and two friends in yellow bike cop jackets and helmets and tell us how you personally would have kept the peace at that fountain, when you first saw Bozo take out his sign and stick it in people's faces.
More to the larger issue of the community we want, how would it do anyone any good to give Shover and the SignStupid lifetime criminal records for something no worse than horseplay at the ol' swimmin' hole? IMHO making both parties cool down and go away wet and thinking is a whole lot smarter.
