Well. The default answer is yes, because we like fulfilling preferences.
If the cow was genetically engineered to want to be eaten by a farmer who wanted to sell meat to vegetarians, then we may want to not buy the meat, just to discourage the farmer from doing that in the first place.
That's what I think, anyway.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
If continuing the discussion becomes impractical, that means you win at open threads; a celebratory top-level post on the topic is traditional.
Poster's Note: omg, it felt so weird typing "2012" up there.