It was definitely a safety hazard. But even if the drivers avoided any collisions, it was a major inconvenience. Total waste of time, gasoline, and brake pads--and if you drive an automatic, think of all the heat generated in the torque converter shortening fluid life and possibly transmission life. For absolutely no reason.
When you go through such an inconvenience, it's really hard not to simply hate cops. Would have loved to see a traffic helicopter report on it. Avoid New Jersey if you can!