The ambiguity fear is born from self interest, of course no one wants the possibility of being legally allowed to be killed. The thing is that the other species don't want that neither, they just cant express it with words nor communal violence.

Meaning ethically we have no ground, if cows could start having rational thoughts /talking all we could answer them is "sorry for killing millions of you all, you have tasty meat, it has nutrients... And stuff... and you didn't complain before".