That looks more like just plain intense rust to me, but it's hard to tell based on that picture. The reason I suggest that is that the scales look to be dyed horn and not celluloid. If it is cell rot, maybe the razor was stored around some kind of celluloid...
Either way, it won't be able to hold a clean edge, because the pitting left over from the rust will put microscopic (and sometimes not so microscopic) holes in the edge.