I would have to google it, but I would not be surprised at all if it is illegal to approach a cop making an arrest and interfering in any way. It's at least reckless. Cops hate it when people start surrounding them or approaching them while they are doing their job. They don't know you or what you are up to. Im sure the cop probably warned him to move along.
For the last time kids, cops don't like being nervous. They are imperfect people with a badge.
The same can be said for protesters can it not?
Absolutely! And they can get punished as harshly as Coleman. But not killed on the spot!