Most people value human life over animal life. Also, I'd guess vegans might advocate making it illegal to kill animals for food (I don't interact with many, so I'm spitballing). The only reason they wouldn't is because it's so far outside the Overton window that it seems like fantasy.
FWIW, I'm a vegetarian who, if made world emperor, would ban killing animals for food, recognizing some caveats and edge cases. But, yeah, it's so far outside the Overton window that I don't think I've ever expressed it to anyone.