That’s what I get for not watching beyond the first few minutes. I still think the police should have left him alone so long as he was standing well out of the scene of the police stop, but once the representative walked into the immediate area, it was exactly as you wrote. The police have a right to control the immediate area for the safety of themselves, the people who are stopped, AND observers.
You were right to be suspicious though and that is what provides a check and balance on abuse.