My question would be, if you're in a place were survival counts so much why wouldn't you have actual items you need vs a basically useless cell phone (no towers in range). Of course I can see if you were boating and the boat capsized or rolled and you lost stuff into the river, yet being in a boat wouldn't you have stuff that is tied down?I can't see this being a whole lot useful as you are likely to have plenty of other bits be it car, plane or other available that can do the same tasks before you start thinking about cannibalizing a phone.Upside is the portability of the phone... I would think that you would gather whatever is useful before setting off on foot however.
I like Al's point about encouraging natural selection I'd be very disappointed if the good folk on this forum didn't have at least enough kit to survive 72 hours just on there keyrings and to not only be found pretty quick, but to have established a modern utopia in the 2 hours it takes for them to be rescued Sent from the astropathic choir.