For the "FDE" positions, it's much closer to being onsite support/tech/contractor. I assure you Palantir is less shitty to interview for/work for than virtually any "traditional defense contractor", which is their comparison (I've never interviewed at Palantir, but know a lot of people there, including their recruiters, and have worked for the alternatives.)

This is all independent of their "mission". (I support national security but not unlimited monitoring of US citizens; It's annoying that stuff like PRISM deters good people from working for government, lowering our capability to respond, and thus hurting national security...)