You and I know this, but I imagine there are many Googlers who take it to heart, and the cognitive dissonance involved in their building war machines may be useful to our ends of reducing American-perpetrated violence.
But what is more evil - that your coworker works on encryption technology that is used to pilot drones, or that your coworker didn't work on that technology, and thus in order to foil a terrorist plot, ground missions were required that ended up costing the lives of a strict superset of people? Don't get me wrong - I don't condone the lengths to which our government uses war technology, but as an engineer, the probability distribution over {my technology will be evil by some metric, my technology will promote good in this world by that metric} is by no means certain.