Hugs as Speech Suppression

Reading Dean Esmay's adventures in Kerryland, where he attends a John Kerry rally themed to the weekend's pro-choice marches, I noted a technique Esmay reports on how attendees silenced and shunted aside counter-protesters:

From my vantage point I could only see that members of the crowd were forming a wall with their placards to block the voices and line-of-site of the party-crashers. Drawn by the conflict, I immediately ferreted over to their position.

This is a confusing image, but focus on the red circle placard in the center; behind it is the face of one of the protestors. The woman in the pink shirt to the left is the other one. What were most likely NARAL representatives linked arms and formed a human chain around the two people, dragging them towards the exit.

You can make out the guy's face with the placard over his mouth.

This is a new one to me, but then I don't attend rallies and demos. Has anyone else encountered this strategy? Is it a Left thing or bi-partisan?

Me, I'd come armed with Mace and let fly if someone tried that. Or trip and fall on one of them, thereby crushing them to death....