That's a losing proposition.I agree that the situation does not warrant public censorship, but if I were the guy that he was comparing to Hitler, I think I would have a few personal issues and would see him in court asking for damages to my reputation.
First, one uncelebrated person holding a sign will generally not constitute a significant risk to anyone's reputation. In that specific scenario, you'd have to prove that enough people actually pay attention to the guy and end up changing their minds about you as a result, to prove damages to your reputation.
Heck, if society takes action against that guy, then they'll have to start taking action against practically all the union members carrying signs bad-mouthing their employers. Often those signs are just as negative and just as ill-founded.
Second, taking it to court does more to legitimize the criticisms against you than undercuts them.
Anyways, the man remained there with his poster for the rest of the day and returned the day after. I have not seen him there since and I'm hoping he has made his point and will let it go.

. I never thought so... The way of thinking certainly seems to write an awful lot of people off as irrelevent.
