Maybe I missed it in the game, but I can't recall if it is ever said whether the bandits knew the St. John brother's were supplying them with human meat.
Jolene was obviously in the know, but she was no longer with the bandits at that point. Did the others know as well?
Unless the game states otherwise I'd guess 'no,' because I can't imagine the bandits entering into an arrangement with the St. John brothers when the bandits could have obtained their own 'meat' if they were cool with cannibalism. I'm guessing the bandits were duped by the St. Johns and thought they were being supplied with pork.