I'm not a vegetarian either, but I think instead of criticizing people for such a choice, we should offer constructive advice. Not, "you will starve unless you eat this rabbit", but saying that food isn't a immediate concern in most survival situations. Sheltering your body, getting a supply of clean water, and signaling for help are the first major concerns of survival. Food comes later. This is the same for everybody, omnivore, carnivore, vegetarian, vegan and cannibal alike.
Oh come on. You have to think about the worst case scenario. Food is a major freakin concern if you can't or don't get rescued. Even I'll be sacrificing my principles. I don't consider rats and maggots to be an option for my every day menu, but if I'm hungry enough, goddamnit I'm going to eat rats and maggots.