Earlier quoted context omitted.
> The only logical endpoint is that humans should just off themselves so we don't participate past one cycle of reabsorption into the Earth's environment. That would obliterate all future human happiness. It doesn't stand up even under a cold utilitarian conception of morality.
I thought the whole premise was that we needed to limit the suffering of other living things that aren't humans at all costs, not about human happiness.
There are various reasons people become vegan or vegetarian, there's no single premise.