If there was nothing amiss, why confiscate the phones?
You can’t possibly be so ignorant as to think the cops were not attempting to obstruct justice.
The phones might have been confiscated as the witnesses took them out to record the events. Unless squad car or other video shows otherwise, there's no proof that the cops confiscated them after recordings were made. I'm not saying that these cops necessarily have clean hands. I'm just saying that based on what I've read, I don't know if there's a case for disciplinary and/or criminal charges.