That means a coyote didn't get it. A coyote wouldn't have left anything laying around. At this time of year, the male would have brought the food back to the den for the pups. They eat it and regurgitate it for, "baby food". At other times of the year there may have been some bigger bones left, but nothing recognizable as, "a lifeless body". This might have been done by stray dogs.
I wondered about that when I first read the article. A coyote kills for food. No coyote is going to kill and leave the food lying on the ground and wander off. Any adult coyote would be able to carry a BF away. They can be pretty casual about this when there is no serious threat to them.