Sitting here thinking about the article brings to mind when the Tea Party was big news in the media. How often was it mentioned about the Tea Party group or members could turn aggresive.
Reminds me of the time Ms Pelosi with her gavel and her members marching thru the Tea Party protest during the health care thing. Could be just trying to entice violence. Did say they got spat on and derogatory remarks made. But that did not fly. Could have been trying to make the Tea Party look like an aggresive bunch.

You will find in the above article where it is mentioned what could happen if the protest turn dramatically violent. How will the demonstrators be looked upon then.

Now it will depend who starts the violence if any.
From the rules for radicals.
RULE 10: "If you push a negative hard enough, it will push through and become a positive." Violence from the other side can win the public to your side because the public sympathizes with the underdog. (Unions used this tactic. Peaceful [albeit loud] demonstrations during the heyday of unions in the early to mid-20th Century incurred management's wrath, often in the form of violence that eventually brought public sympathy to their side.)