On sebenza's with inlays. That milling is a stop or transition point from the polished surface to the bead blasted surface. The lockbar on Crk's are always blasted. Imagine that area past the milling being polished under the clip? It'd be tough to keep friction on the pants pocket.
I suspect this is the same for the inkosi now as well. The inlaid micarta inkosi are all bead blasted while the inlaid carbon fiber inkosi are polished up to that milling point. Basically, Instead of making a bunch of lock-sides for the inlaid inkosi models with and without those millings they make the one you have there for all, then polish the models that are necessary up and to that point.
The clip is really tight fit into that seated pocket. Needs a bit of a wiggle to get it to move with the screw removed. Sometimes it may even need a little nudge (pry) from underneath. If your going to do that I suggest a some plastic utensil, chopstic, sturdy thin piece of wood to prevent scratching.