“the 10-yard-wide canyon next to a stream where they had been camping”
I thought the BS taught common sense?
Not a place where I would have set up camp.
It was probably an established wilderness camping spot. To camp down in the Grand Canyon, wilderness permits are required so they can control the amount of people down there as it's a very special ecosystem. Also, there are strict regulations about where you can camp, esp. when you have a group of people. (I've camped down there twice at Bright Angel Campground-really a neat experience.)