Palantir is deeply entrenched in the surveillance state. Though they may come at you with a decent offer, I believe it is ethically impermissible to use my skills in order to contribute to the deprivation of the human rights of others across the world.
I do not have much positive to say about Facebook either, except that the bulk of their revenue does not come from three letter agencies. And they have in the past and will probably continue in the future to solve some interesting challenges in scalability.