they were told to use their own urine (which is sterile) to wash their penis and get all the sand etc. out/off.
That's pretty bizarre. Yes, it's sterile when it comes out, but it wouldn't take long to attract a hell of a lot of bacteria outside the body. We all know what dry pee smells like. I really can't imagine who devised that little gem.

Personally, I don't see the point in the whole operation. If it needs to be done medically, without a doubt do it. But we don't go about removing other body parts on the off chance they may have something go wrong with them.

This is probably too much information, but as an u/c male, I know when the skin is back and the glans are rubbing against underwear or whatever, it is bloody uncomfortable. So I assume to tolerate it forever, a certain level of desensitisation occurs.