I understand what your saying with your force continuum, but my thoughts are, if your going to use pepper spray or any other alternatives on a bear, its because its attacking you, and a bear or any other wild animal going to attack you in my opinion requires a quick and immediate end hence the use of a firearm including your 870 Remington shotgun being a good home and wilderness defense firearm. Unless ofcourse your dumb enough to try and stop a bear from eating your lunch with pepper spray, then well there are Awards for people like that.
I don't think you can compare a animal attack in the woods to a attack being done by another human. Simple fact of the matter is, no matter how hard you try, taking a baton to a bear and trying to "win" the confrontation wont happen. So how I see it its best to get to the highest level of force without wasting time that will end up costing you your life in a animal attack.