Well taking war prisoners, I think its normal to all houses. (points at liberty possbile experimetns at alaska, not only nomad).
Why to keep a prisoner and feed it then it gives no profit?.. So it comes into two ways, push it into forced labour or kill and sell/use their organs. I think killing prisoners and slaves at etna for organs to corsair wounded pilots is quite logic.
And about dislike slavery? Well any humanist views are not welcome here. Now why is this?.. Corsairs are far from humanic entety. They kill, they rape, they rob, they exort they torture and such. And now someone is telling that they found a bit of pitty to the slaves?... what?.. no way. Only reason they ahte slaves is becouse Outcast economy stands on it. Not becouse they see it as dirty practise. One more point why they might dislike slaves is lack of food, btu then no-one is stopping them to kill the slaves for profit. Ech?
And about canibalism, in the days then Corsairs suffered from famine very hard, some of the people who were about to die, agreed to be eaten. Its not like corsairs liked that or done that becouse they wanted.