If he could [censored], he wasn't dehydrated. When dehydrated, the body recirculates urine, and the urge to [censored] shuts down or can be easily overcome. If you [censored], you take water out of circulation. This idea is really a no-brainer.
I am absolutely convinced that "survivors" who drink their own urine have fallen prey to a non-viable "final option" or "alternative" which can ultimately serve as nothing more than a debilitating attempt to make up for the fact that one is mortal (not a closed-system) and perhaps has a weak will to begin with, like sucking on a pebble to create the illusion of extra water in the mouth. Pebble sucking might actually have some benefit though, as it might serve psychologically to stimulate reabsorption from the bladder into the bloodstream, and even as stimulus to keep the mouth closed which would keep the person from losing water via evaporation from the mouth, as well as possibly to slow the person down as he or she attempts to breathe solely through the nose, which might reduce sweating. Either that, or some people are simply uneducated and/or that that education is inacessible to the person who's mind begins to shut down in a survival situation such as dehydration. Quite simply, a survivor drinking his or her own [censored] is literally an ostrich thrusting its head in the sand. The only way to combat dehydration is to increase the amount of water in the body, and urinating causes water loss by evaporation and even by "missing" the canteen. It is much more efficient to keep what water remains in the body by not pissing and not sweating and not breathing with the mouth. It's already there, so why excrete it just to reintroduce it?
On the other hand, to drink someone else's [censored] would increase the amount of water in the body, and might be of some value. Here the only logic is that it is better to not die of thirst than to have a little extra strain on the kidneys.
A fellow survivor would not likely be a suitable [censored] donor (I wouldn't give mine except in certain situations, i.e. loved ones), but a camel might. But, I would probably drink some of the camels' blood if I had that option. I would think that blood would be more thirst quenching than [censored], but I would be interested to see a link to information concerning salt content, etc.