Several updated articles on the story are citing officials saying that the stomach and intestinal contents of the bear that was feeding on him are consistent with that bear being the one that attacked. In addition, they have determined that the bear the man was photographing (when he ignored park rules) is the bear that was feeding on him. So, all current evidence points to him being killed by the bear he failed to leave alone.
Stomach contents should be no problem since the bear was feeding on the man. Identifying that bear as the one that was grazing in his photographs I think would take a bit more time for a definitive conclusion, and as yet I haven't seen that in print. There was another bear near the site that ran off on the initial fly over, and certainly that bear cannot be discounted as a possible suspect in the attack. Forensically they would need to match the wound that killed him (if that's still possible) with the teeth or claws of the bear that was shot. Certainly circumstantially the info I've seen so far point to this bear, but I think more time is needed before they finalize a judgement.
Yes, he broke the rules but this was a predation kill of a human. This is not the usual grizzly attack where the threat is neutralized and then the bear leaves. He was definitely in the wrong place at the wrong time with the wrong bear.