One very important difference between science and engineering is that in science you need to improved knowledge but demonstrating that something is true, when in enginering you need to start from something true to build a whole systems that works accordingly to your needs !
Even if tweezers could be demonstrated as efficient to push and carry heavy items such as spacecraft and warplanes, it would remain a long, painful and expensive way to run before designing a more practical, reliable, affordable.. system than those used in our present times. Maybe in half a century ?