From a safety POV we already eat processed food made from leftovers of fishes that eat chickens (leftovers) that eat porcs (leftovers)… or the other way around.
From a moral consumer POV I would definitely enjoy more a food (plant or animal) feed from another human rests than feed from another livestock slavery facility.
From a “consumed” POV, I won’t care less.
I get there’s a lot of people with beliefs that think they can’t accept that. I may be downvoted for that : some decades ago, _a lot_ of people had the belief they “can’t live in a society with same sex mariage”.
I respect the convictions of others as long as they don’t tell me what to do or not, especially when I’ll be dead.