They are given a law to enforce. That's their job.

Maligning them in this situation is simply a mistake. I thought they handled it perfectly, giving the vendor ample opportunity to apologize and take the stand down.

They refused to do it and because combative. So, they get arrested.

The only part that was not acceptable was when the cop tried to block the cameraman on several occasions. That's a violation on their part, but, apparently, they'll do it every time to get rid of any evidence of their misbehavior. However, there was no misbehavior in this instance other than the attempt to physically block the camera.