I agree. He was probably ordered to do it. However, he chose to follow that order. He could have voiced his concerns and said "I am not comfortable with this". He did not. He actually arrested a man who was doing nothing wrong. That's a big deal. There should be consequences for this behavior. It will make other officers think twice if they are given similar orders in the future.
Or he could have made it clear to PP that he didn't really have a choice and tried to work an accommodation for that night until details could be debated the next day. Maybe even make it clear that they were welcomed to be in Lawyer's Mall, regardless of permitting, for the evening. Granted, this might not have been acceptable to PP but it would have been reasonable to offer. A reasonable and Constitutionally aware officer would have made efforts in the spirit of protecting rights rather than suppressing them. The video does seem to suggest that Sgt. Pope had received his marching orders, was possibly a little bitter about them, and had steeled himself for the bitter pill he was expected to swallow.
-Andy