I'm not entirely dismissive of the argument. I do think it has a point. Why do pigs get to live? Because they look vaguely like us? Fuck you wheat! You eyeless, legless monstrosity! I don't care how much you enjoy swaying in the wind and basking in the sun. You're literally toast!
Everything wants to live and is afraid to die. But I do agree dying screaming pigs is much more unsettling than millions of wheat stalks getting slaughtered by a combine.