Firstly, NEVER get into an argument with a vegetarian or a vegan. They are ALWAYS right. This isn't someone "thinking" they are right - their argument is fucking solid -

As humans, there is ZERO need for us to exploit animals for our consumption other than human greed.

Think about it. All "goodness" from meat can be gotten from somewhere else.

The only thing I could come up with, is that I dont support or condone the treatment of animals for the foods we have, but as a omnivore, I needs me my meats.

But yea, vegetarians are the only real fanatics I know who can get away with being nutty cause they are fucking right.