Based on all the other reports I’ve read about this attack, I think “freelance photographer” is the wrong term, as it implies that the person was some sort of professional photographer. Sounds like it was just some random person on the street, who asked the cops to take a picture. I’ve lived in and around NYC for most of my life, and I see that happen all the time.
I doubt the photo guy was involved in the attack. From other reports, it sounds like the attacked had been milling around for quite some time, likely waiting for the right opportunity.
According to the "Gothamist",