The real ethical dillemma is this: people working for corporations and governments are asked to develop nasty stuff that will directly be used, and then they try to justify it by saying that what they're doing will be done eventually. However this doesn't hold water because by doing it themselves, today, they are making it happen sooner than it would have. Obviously everyone will die eventually, but we don't want to be killed because "sooner" is a significant thing.

By comparison, academics working on their own making very little money with no pressure to be evil do not have a problem.