But "hardened" and "veteran" don't sound like descriptors of people who would gleefully jump into the morally grey and black. They'd deal with death and killing better than the average joe, but that doesn't mean they find joy in it. I haven't read the whole trait list, but things along the lines of 'evil' would be better — sadistic, brutal, etc....
And it shouldn't be the lack of a debuff, but instead these traits should gain a happiness buff or something.
It'd be interesting to see colonies with certain kinds of people naturally evolve into a cruel dictatorships because of who is involved. And to also explore the conflict between different characters with different moral views regarding these topics. Perhaps even coups. I know we're in control, but characters can go crazy. It'd be interesting to see characters change the status quo, and rise up against each other because of their relationships, beliefs, and actions. The player having no control to make them stop (because they let it get to that point), and would just have to work with the after effects.