We learned that trick way back in the Sixties: As a long-retired "student radical" from the last millennium, I know a little about protest tactics. Our "street actions" in the Sixties had little to do with political issues in a direct sense. There was no sincere effort to educate or persuade with our signs or syncopated chanting. We were realistic enough to know that we were just talking to ourselves and that policy was shaped in places other than street corners. We also knew that an uneventful "peaceful protest" was a gigantic snore that would go unreported in the press.
Our real goal in taking to the streets was to provoke the police to behave badly and hopefully produce the classic money shot of a protester (preferably young and skinny) being walloped by a policeman (preferably big and resembling Darth Vader) that could lead the evening TV news. We could then use the tortured logic (most effective on the better college campuses) that anything associated with the big bad policeman (a trade policy, military action, or whatever) was evil.
The cops knew that was the game plan and had the anxiety of knowing that within the swarm of gullible and generally harmless protesters lay an unknown number of cynical agents provocateurs intent upon sticking figurative and literal needles under the cops' skin to goad a reaction. If the "innocent" protesters had an ounce of self-awareness they would have realized their sole function was to provide cover for these mini-terrorists and gone home. But that's asking too much. It was way too much fun assuming the self-righteous mantle of the martyr and being written about in fawning media coverage of how "the man" thwarted their rights, blah, blah.
Been there, done that many years ago. It's a shame this tired old trick continues to manipulate supposedly well-educated and skeptical journalists.