And if you'd read anything that I have posted in this thread, instead of just skimming through to find the points that you want to disagree with, you'd realize that I'd already addressed that very point.
Elves do not eat sentients. They eat their kills.
I make the point over and over because people don't seem to read it the first time.
Look in your entity_default.txt file. You will find in there an entry for the elves, on their ethics.
[ETHIC:SLAVERY:UNTHINKABLE]
[ETHIC:EAT_SENTIENT_KILL:ACCEPTABLE]
[ETHIC:EAT_SENTIENT_OTHER:UNTHINKABLE]
To translate that from raw speak, let me tell you what this means for the ethics of our "friends" the Elves.
Slavery Unthinkable: They will not engage in the traffic of sentient beings forced into servitude. They do not keep members of other races as chattle.
Eating Sentient Kills: They WILL eat enemies they have slain. This applies only to those they have personally slain in battle. If an Elf kills a man, it is for him to eat. Other Elves will not eat that kill.
Eating Other Sentients: They are not cannibals. They do not eat their own, and given the opportunity to eat the meat of something that once could talk, they will decline. It is a reprehensible act to them.
So basically, offering Slaves to Elves, and telling them that it's food, would most likely get them to attack you. They would be so offended they couldn't speak clearly, and would almost certainly think that you were so depraved they'd declare war.
Ironically, they feel the same way about animals. They will only kill an animal if it attacks them, in other words [ETHIC:KILL_ANIMAL:ONLY_IN_SELF_DEFENSE]. So they don't even actively seek out meat. They won't kill animals unless they're threatened, which leaves out the entire concept of them being carnivorous, let along cannibalistic. However, their ethics on plants are even stranger, considering this. [ETHIC:KILL_PLANT:UNTHINKABLE]. They can't bear the thought of so much as damaging a blade of grass.
So it would seem their only source of protein is creatures who attack them, which they kill in self defense, then eat. Whether they're a sentient being or not does not enter into their conciousness. They can only eat things they've recently fought with.
So I didn't hijack this thread with an Ethics argument. I pointed out, simply and truthfully, why the original posters idea of selling prisoners to elves is not an option, either for the Elves OR for the Dwarves, for multiple reasons. It just so happens that this reason is an Ethical one, from both sides of the fence.
Also, I'm almost willing to bet that if you changed both Elven and Dwarven ethics to allow Slavery, and to make the eating of sentients acceptable, that this behavior would be possible in the game as-is. You might even see them chow down on gobbos you sold them.
But, as I stated, due to the ethics which are already in the game, this is not an option.
TLDR; I didn't derail the topic with an Ethics argument. This suggestion is IS an Ethics argument.