Alinsky tactic. Saul Alinsky once advised leftist student protestors that were totally against any member of the GOP to dress up as KKK members and go to a speech by Nixon at their university. Alinsky advised them to cheer and flash signs supporting Nixon during the whole speech.
There was a report that a protester outside of the Dingell office was actually a Dingell staffer/volunteer or something. This is a very common tactic for the left.