Here's the thing.
The paleo diet simply consists of foods that are not grains or legumes or processed foods.
This diet can take any number of formations -- of which the primal blueprint is only one. There are low fat paleo diets, and there are high fat ones, and everything in between.
The diet can be vegetarian, but under the guidelines of the primal blueprint, it is difficult to reach the ratios that mark discusses *unless* one is eating some meat. It just makes it easier. It's not an absolute.
If you believe these studies -- which I don't, btw -- or you have any other reason to not consume meat, and you don't want to eat meat, then don't eat meat.
It's no big deal, honestly. I go days without eating meat, and then days when I do. It's really and truly no big deal.
Do what you want.