I agree with you pretty much everything you said, I just think that drawing a strong distinction between any one species and every other one mischaracterizes the situation. Evil is a human construct that applies as poorly to human behaviour as to the behaviour of every other animal, for the same reasons.
If you'll excuse me simplifying your point, "They're animals of course they do that, evil doesn't come into it" is not quite as accurate as "We're all animals, evil doesn't come into it", to my mind at least. Because OP didn't just misunderstand an aspect of non-human animals, they misunderstood an aspect of how life works.