The hole also:
Enables the knife to be used as the top spindle support when starting a fire by the bow method. (Insert pointed top end of spindle in hole.)
Allows a balanced center point for attaching a line when you fall in an old shallow well while hunting and need to use the knife as an anchor to throw between boulders so you can climb out.
As a sighting hole when using your polished blade as an emergency reflector mirror. (I believe that I read this somewhere.)
As a fulcrum, as when you are hiking alone and a boulder falls on one of your arms and you have to use the other hand to amputate the arm.
You tie a shoelace to a fixed object and through the hole, which gives you increased leverage with the one hand.
I am pretty sure that the Busse patent application spelled all of this out.