The animals are going to do what they're going to do. The predators will play predator games. The prey will play prey games. The parasites will play parasite games. Concretely there is one exit: the singularity. Almost anything is justified to reach that goal.
We already have regular holocausts. Like clockwork. Do you know what a holocaust is? If that cost is already sunk, already RECURRING, do you really think your minor moral scruples hold up as valid sinks of energy? Play to win.