The main reason the paleo people get flack comes from trying to claim historical accuracy when science has consistently shown that claims about e.g. how long humans have been eating grain or dairy products are off by thousands of years.

See e.g. http://www.scientificamerican.com/article/why-paleo-diet-hal... or dozens of subsequent pieces.

The better way to phrase this is to avoid trying to claim unique merit: “This diet works for me. Maybe it will work for you.” That keeps the truthful part but drops the magical claims about why everyone else's choices aren't as valid.