If you have been following the the comic story, you know the sheeps live in a closed high-security society and in this society what it means is the opposite of what it seems. While going to McDonald's seems to be a cool thing to do and to hang around a little having fun, in fact that means being killed and becoming a humburger.
Summarizing, this is a criticism against how most of the the things that look good today are in fact tricky, it has nothing to do with meat-eating.
Listen, I'm not against vegetarianism. Please, don't take it to the other extreme and call me an anti-vegetarianist.
