Slash their tires every time and these creeps will give up. Lay a hand on them and they will sue you to oblivion which is their real racket. If you are caught slashing their tires prosecution will be minimal because everybody hates these rats.
It probably won’t work a second time. Next protest, I’m betting they’ll have a small, barely visible videocam.
Why do you think that? They will probably sue whoever it was that slashed the tires. I'm surprised they didn't have surveillance on their van just to catch people, so they could sue them. IT's how they make their living, suing people who lash out at them.