Far fetched ill agree, but im very confident that there have been live people who have done very close to exactly this.
Yes, as I also said, you do hear of it from time to time. But for every person that survives, there's probably thousands that died from severed arteries and limbs. And those are people with immediate access to medical treatment...
Loss of blood, infection, dehydration... he wouldn't have survived. Then sprinkle in a 4 story climb down the side of a building and evading/fighting hordes of zombies. Absurd. His return, and the Governor, were nearly enough to turn me off to the show.