Drop 100 million Fire Ants on them.
Ants on a helicopter?
Besides, a good gust of wind and you just fireant bombed the rally! Idea has merit but needs work.
I say get good videotape so you can distinquished who is blocking the road vs those that are just attending.
Dump florescent dye on them. And then set up road blocks and arrest them one by one as they try to leave.
Screamin’ and Dancin’