I agree that honor is a pivotal aspect when it comes to corsairs, but within reason and not as another "corsair cryptonite" like the food thing. People are way too simplistic in their approach to these two aspects, as if it is a "let me go or u no rp" card.
Here's an example on my take on Corsair honor: There is a certain pirate in O3 I tried to remove via my usual brutish approach ('cause he is not a Corsair = not worthy of honor), and when I realized I didn't stand a chance I threw in the towel and broke off. Now when my character comes across that character, he is treated with great respect and honor - because he earned it. That is roleplay to me, reacting to situations and events in-character, rather than just follow some template regarding "how it ought to be" because that is really not roleplay in my book.
If I had gone into that encounter with "great honor" and much respect for my opponent as a starting point, there would have been no real encounter; it would be meaningless (both mine and his characters wouldn't have progressed) and just a tiresome stalemate in the cookie-cutter way we create and present our characters and factions. I like people to be creative and think for themselves; but that is rarely appreciated here, I know. Everything has to be black or white here.
The same with slaves, saying flat out it is "dishonorable" or "morally wrong" for Corsairs to get involved in the slave trade isn't making that much sense at all. Yes I see that slaves use up valuable food and that Corsairs wouldn't have any interest in a slave-state like the Outcasts and would probably treat their slaves a lot worse - slaves would be commodities, subjects unworthy of any doubts and discussions regarding honor or morals, like a lower caste outside of society.
I can't see how it would be an issue that some Corsairs choose to keep the fittest and strongest of the prisoners of war they take rather than just flat out executing them, if they can make credits on them I fail to see why not other than random corsair laws and glorius un-realitistic and un-reflected ideals of morals and honor that leaves out any and all nuances - and nuances is what makes most/all roleplay plausible if you ask me.