So... is the complaint that a company fills this niche, or is it that of all possible companies doing this business, Palantir is particularly immoral?
I'm not sure it is possible for effectively a (cyber-)weapon producer to say, ah youre using our weapons immorally, we wont sell them to you. This is the domain of government regulation and export control.
So I personally wouldnt expect the contractor in this space to stand up to some high moral standard. I think the best we can hope for is compliance with laws, and there's your problem. US doesnt care how badly people get abused by the weaponry it exports, so long as IP and military secrets aren't leaked. Palantir is safe from US regulation.
Are other countries better? Some for sure. Germany blocked Eurofighter exports on ethical grounds. I'm not judging if they were right or wrong, but merely that they forewent cash for ethical points.
But most will sell anything to anyone, so long as the price is right.
Im not saying Palantir is a nice cuddly company, only, hate the game not the player.