Is our dominion over animals unethical? I'm sure you can imagine examples. The point is to show that our actions in respect of people or babies or animals or dead bodies or psychopaths do in fact take place in a moral sphere independently of any assessment of individual criteria such as future moral comprehension. The concepts of right and wrong do in fact, in real-world communities, apply to those actions. I take you to be arguing either (1) that they should
not apply, that perhaps people all over the world have made a mistake, or (2) for a meta-ethical position whereby you think that the only reason we apply the concepts of good and bad to our treatment of others is that we recognize that they are, or will be, moral agents--that they have individually satisfied some criteria (and hence that principled veganism is based on a mistaken assessment). If your position is the latter, then it seems to me that our moral concern for people with severe cognitive impairment, for the dead bodies of our loved ones, and for pet animals stand as counterexamples.
You do not treat a person well because you've established that they have the mental capacities that you deem to be requirements for morality. And if you treat a person well on that presumption, you do not suddenly treat them as morally insignificant if you later find out that they lack those capacities.
But my wider point was that ethics
just is about human actions concerning the things we value. We value pet dogs and most non-psychopaths would not wish to see them tortured. This is an ethical matter despite a dog's possible lack of moral comprehension. Do you disagree?
EDIT: The even wider point is that I think you
are appealing to an intuition that is close to my own view, which is about species membership and the moral sphere of human society (which includes animals, though not as moral agents). I.e., I think that individual capacities are a red herring.