Presumably similar to how it works for the professional Mechanical Engineers and Electrical Engineers they already employ. Ethics are subjective and nuanced. Ethics are also different from morals. Some people can live with the moral quandary that their work may do harm to innocent people and still have the ethical belief that they are doing the right thing generally and that their work does more good than harm. (I'm not one of those people myself with regards to the military-industrial complex, but I respect my friends that are have sat with their morals and weighed them into the ethical frameworks of how they do their jobs and what they feel about doing their jobs ethically.)