What relevance does the weapon being used to counter a criminal in action? If Rand would have said that's its ok for the police to SHOOT a criminal coming out from a liquer store with gun in hand, would that not be a problem?
The fourth amendment has nothing to do with what weapons you can use against crimals in action. If someone threatens to kill other people and has a gun in hand I don't give to shits about is he's killed with a handgun or drone. Why would I? And more importantly, why do you?