Reliable and secure communication technology is what enables the military to function. Without it, all the weapons technology in the world wont do you any good. So on a moral level, if you are against war you should actually find working as a researcher on communication technology more reprehensible than working on weapons. On an intuitive level I would guess that the breakdown or compromise of military communication has resulted in a greater loss of life than advances in robotics.

The reason why I'm pointing this out is that the real world isn't as simple as "a bunch of dickheads trying to strap guns to [robots]". You're making a simplification because it's convenient, but that simplification is morally inconsistent with approving of DARPA's work on the Internet. The fact that technology has a dual use is something we all have to deal with as researchers. But I don't think it helps matters by treating the issue as a binary.