If it was only about avoiding suffering/pain and not the dying, would you be okay with farming children for eating?
They will live happy lives pampered and cared for, running around in the backyard until you press a button and child drops dead. Takes 1 microsecond to die.
It's obviously absurd, but you're making that decision with the animals you eat all the time. A chicken (probably) is less self aware than a cow, but we do eat cows.
But how do you decide that another being is un-self-aware enough to be eaten?
Which takes me back to the absurd. If human meat was tasty (I read it isn't), would someone with downs syndrome be morally ok to eat? How about someone in a vegetative state?
If the sliding scale of self awareness is the deciding factor, we might as well eat less aware humans.