Every choice involves compromise.
I am a vegetarian who uses animal byproducts. On the one hand, I don't want to contribute to the suffering of sentient creatures caught up in and casualties of industrial farming practices. At the same time, if McDonald's is going to keep making Big Macs out of the innards of such creatures, I am content to use the byproducts, figuring (or deluding myself into believing) that demand for byproducts doesn't fuel industrial farming the way that, say, the fast food industry does.
Do I draw an arbitrary line? Certainly. Does this make me a hypocrite? I hope not.
This being said, there's no need for omnivores to slander vegans in order to make a similar point. The discussion was starting to de-evolve in to stock stereotypes of emaciated liberals with wagging fingers...