The first time I heard about Paleo was in '99 when I was in college, vegan, and working at a health food store. Some douche asked me about some supplements. Somehow in the conversation, he asked me what I thought about the meat that the store sold, and I replied that I had not tried it. He asked why, I said I was vegan. He got in my face and was about as evangelical as a fundamentalist Christian about why my eating habits were terrible. Dude had greasy chi, made me uncomfortable just being around him. He said that I was stupid for following a vegan diet because we were meant to eat like a caveman and that meant meat. I just turned away and continued my work stocking the shelves. He persisted for a few minutes with his ridiculous diatribe to my back, and then eventually sputtered indignantly that I would not submit to his abuse, and he oozed off somewhere else. The worst part about that job was that a certain percentage of the customers were just batshit insane.
If your diet or any chosen part of your lifestyle is going to turn you into an asshole who berates complete strangers for not following your path, then maybe you ought to look at your life and figure out when you became such a huge asshole. If you can contain yourself to remain smugly silent in your knowledge that yours is the One True Path, without accosting random people in your path, then knock yourself out with your crazy diet.