Its a funny story but I have a feeling that the stool falling on the fox's head did the fatal damage. It's tough to believe a chicken's beak could penetrate deep enough to hit a vital organ or artery to kill the fox. The 'death by a thousand pecks' seems rather far fetched. Glad the fox got what was coming to him though.
The picture show's that it is false. The foxes face and two front legs were gone. Chickens cannot crush a scull and so the fact that it is gone means something else. But for sure those chickens did not kill that fox it looks like his face got blown off, or bit off by a dog.