I don't identify as a pacifist - quite the opposite, I think we should fight Project Maven like hell. The DoD wanted to fund a communications network? Cool. A private company recruiting 10k+ engineers on a cool, creative "don't be evil" brand, and then backdooring their work into use by a defense department is not cool (I'm not saying the company doesn't have the legal right to, I'm saying it's a jerk thing to do).
Sharing research, open-source code, etc is fine, and of course defense is free to poach away top engineers. But they can do that through recruiting, not their IT budget. Or if Amazon and Microsoft want to do the work, that's their choice, I never wanted to work at those companies. I think Google is missing a huge opportunity to define itself uniquely here by not canceling immediately.
I believe true neutrality is to do defense for nobody, I would like there to be a premier technology company that international colleagues can work at that serves no military. I wonder how many of my coworkers can't express their solidarity because of their visa status, because the insane cost of living of the bay area, etc. I don't know.