If you are just a bystander that is all well and good. If you are standing there with two friends and one friend decides to go nuts on an officer, are you still a bystander?
The story didn't mention anything about the other people, where they were, or what they did at the time of the struggle. I just figured police would just haul the whole group to jail and let prosecutors sort out what to do. They may not. If it was all in just a handful of seconds, I doubt the others would have much problem. That is not a scenario one could plan for.