In all fairness, they were inside a terminal and possibly disturbing the peace/disrupting business (hard to tell fully from the video), which is not something you can do even as a protest. So the cops had the right even before this law to make them leave.
OWS also has a bad habit of stuff like this that causes police to get involved. When things get heated, that's when all the cameras come out and makes it look like the cops are abusing power, when you never get to see what started the conflict to begin with. Had they complied with police orders in the first place, it never would have escalated to that point.