They've been trying to provoke violence since they started - but cops are on to their games. Showing force would play into their paranoid fantasy of melodrama... don't give ‘em what they want.
Ignore them - or smile or laugh at their pranks. Carry a sign that says, “com cars aren't toilets’ or something like that .... That's what they hate.
Showing that you have the means to defend yourself does not cause violence....
You must believe guns are bad, and that they cause violence.