"For one thing, the law makes it easier for the government to criminalize protest. Period. It is a federal offense, punishable by up to 10 years in prison to protest anywhere the Secret Service might be guarding someone. For another, its almost impossible to predict what constitutes disorderly or disruptive conduct or what sorts of conduct authorities deem to impede or disrupt the orderly conduct of Government business or official functions.
Sorry, its well established in law that one cant utter fighting words or egg another on (create the situation) and then claim innocence or self-defense when theres retaliation.