think fast

Justify killing animals for nutrition when...

1. you don't have to (beans/rice, eggs, dairy, gluten, etc. provide enough protein),
2. you accept Darwinism and the conclusion that humans aren't ``special'' aside from their abilities (and the corollary that ability doesn't determine one's right to live), and
3. you hold empathy as a reasonable virtue

Also, since we aren't any special and we are omnivorous, we are as entitled to eat whatever we can as animals are.
You could use that to justify anything. Rape? Primal urges for reproduction. Murder? Competition for territory and mates.

If an intelligent being had somehow evolved to spray toxins every time it sneezed, it'd probably be a good idea to wear masks as a permanent ornament. Controlling nature is not a bad thing to do, and anyone making such an argument (a naturalistic fallacy) is acting hypocritically unless they're Amish.