Because he upholds an instrumental reason as practiced by neoliberalism, predicated on the bourgeois conception of rationality. I don't think that it's possible to ascertain what is a subject in a moral question in the postmodern world (in his utilitarian view at least), and there is no way in which to conceive of a "right life" without negating the elements that be in the current society, as the categories we're readily presented with are already wronged, and shaped to harm anything that isn't capital, or one of its conduits. Hence the need for a worldview and a practice that thoroughly negates or imagines beyond what is already here. His anti-theist view is in line with this, although im not religious, the idea that social change arrives without myth or any sort of collective spiritual "revolution" in values and beliefs is unlikely - so just as the French revolution converted the divine into constitution, a new world will change all that we take for granted.

I honestly don't think the subsumption of animals under capital will end because we "think" about the issue in a different light, or by some means deem it an unethical practice. There is no ethical control over production and distribution because the abstract and increasingly fragmented processes of capital that are responsible for this isn't something that responds to emotional reason. Meat is an extremely lucrative market, so the small nudge in demand that a few vegans will make will never be a force that can effectively reckon with the infinite resources they can throw at marketing or dominion of territories. Growth, and so meat, are a part of the infrastructure of the world. Good for capital, not good for the environment or animals, including people.