If you think that a person is about to turn on a (to your way of thinking) insufficiently Friendly AI, such that killing them might stop the inevitable paperclipping of all you hold dear, how do you take into account the fact that they might have outwitted you by setting up a dead man's switch?

If someone with a facemask is pointing a gun at you he might just want to present it and ask you if you want to buy it, the facemask being the newest fashion hit that you are simply unaware of.