You miss the point. The concern is not that it will get out of hand. the concern is Beijing ordered it to happen in the first place.
The US continues to weaken in the world. Obama is pleased.
You’re absolutely correct. Nothing like this could happen without authorization from the Chinese polituro. They were sending a message. There was no danger to the Ambassador, but it was an “in your face” insult at a time when Americans (if not the American government) still have an open wound because of what happened in Libya.