I don't think that it is dissing vegetarianism as much as it is dissing extremists.   The second verse has the singer committing acts of violence in order to stop violence.   Think Unibomber, radical abortion foes, radical conservationists who will spike trees and other extremists who seem to contradict their own beliefs.

Woody did say "I hate a song that makes a person feel small, no good...etc.", but even he threw barbs at those that he felt deserved it. Besides, the Arrogant Worms are not making fun of vegetarians.

Is the writing good? Perhaps not, but again I think you need to see them in performance to truly get the point. Reading the lyrics as posted does not convey the intent.

I am reminded of Groucho Marx remark, which I paraphrase, "If you have to analyze humor, it isn't funny".

Ron