I think it's just a principle thing. The founders built Google on a policy of "Don't be evil", and war-robots may be considered evil depending on your own perspective.
My point is that you are still building war-robots, you just aren't getting paid for it. The military will just pay someone else to build the military version.
In 2015, we made great progress in identifying a person with a gun:
In 2015, we made great progress in identifying a person with a gun:
http://www.bidnessetc.com/59108-microsoft-corporation-beats-...
Bet this technology soon makes it into drones.