He should have let this "officer" arrest him for trespass. At that point I'm sure Hannity, Rush, Malkin and others in Conservative Media would have had a field day shining the light on this creep. This is precisely the tactic the left would use and it's precisely the tactic we need to use each and every time this sort of crap happens. Free speech means free speech, not speech that some accept and some don't.
I'm sure that the gentleman with the sign had to go to work the next day -- the key difference between Conservative-activists and their Liberal counterparts.