Didn't think I would ever be out-pednanted, but leave it to this group. SO of course I did an extensive search on the name of the route in question, and the one spelling that does not come up is "Mountaineers'". Mountaineer's, Mountaineers, Mountaineering, sometimes not even capitalized, but I did not find one more instance of "Mountaineers'". Although I agree with the logic of what each means, it leads to a different conclusion. It really is in fact the route of one Mountaineer: the Mountaineer himself, John Muir, who established it.
