Actually some of the SOG blades from Veitnam were sterile for that very reason.
Unless you were parachuting into Cambodia with your sterile SOG in your teeth you probably would not see one though. Mostly the sterile knives are so no one can prove that US forces were somewhere they were not supposed to be.
I like that the knives are sterile it gives them a more serious look and makes them cheaper. It also makes it more special when they do put a logo on stuff like the SS4.