Drexler was worried about just those sorts of problems, so he put off writing up his ideas until he realized how developments in multiple fields were heading in the direction of nanotech without any realistic criticism, that's when he wrote "Engines of Creation". He also made the point that there is no really practical way of preventing the development of molecular nanotech, there are too many reasons for developments leading in that direction. If one nation outlaws it, or too heavily regulates it, it will just be developed elsewhere, maybe even underground, since advancing technology is making it easier and cheaper to do small scale R & D.