The original thread here was about Matt Cutts and his decision to work for the DoD, not about you.
You offered your work experience as a specific example of how you could work for the DoD without being involved in killing people. I think there's no good way to discuss the validity of that example without being a bit callous, since it involves a) your personal work b) discussions about killing people c) politics, but I think the commenters here handled it appropriately. I certainly think it would have been worse for the discussion for it to go unchallenged.
I disagree. I don't think people realize that the various militaries deployed in Iraq and Afghanistan actively clear IEDs from civilian neighborhoods that hurt and kill civilians. They are not always placed for military attack but many times insurgents attack civilians with them.
The commenters are largely tone deaf in this arena. They never call out any large technology companies for doing the exact same thing. Google and others actively work on the same projects. They are all DoD contractors. HN seems to think anyone involved in the DoD complex is accountable to some degree for military action then completely ignore all of the west coast companies involved in the exact same thing.
Then I'd like to clarify that I'm also objecting quite strongly to all companies contracting to support the US military's ability to wage illegal wars. I do think there's a fair portion of HN that is loudly unhappy about, say, Palantir. I would never work for them, although I'm not as loud about it. I think you're right that I should also never work for Google.
(Also, war is messy. I know that the insurgents also kill civilians, and I'm certainly not supporting them any more than I support the US military. I'm advocating pacifism, and if you want to say "well, pacifism doesn't work because other people want to wage war", sure, that's a debate approximately as old as the idea of pacifism itself.)
You offered your work experience as a specific example of how you could work for the DoD without being involved in killing people. I think there's no good way to discuss the validity of that example without being a bit callous, since it involves a) your personal work b) discussions about killing people c) politics, but I think the commenters here handled it appropriately. I certainly think it would have been worse for the discussion for it to go unchallenged.