Guyenet seems to make radical concessions - he really is not advocating a paleolithic diet at all for most people:
Should we all eat a hunter-gatherer diet? Not necessarily. Human evolution did not end with the Paleolithic era. Each person carries a particular set of genetic adaptations that result from the unique dietary environment of his own ancestors, so it's important to emphasize that traditionally prepared grains, legumes and dairy can be healthy foods for many people.
In fact, he is arguing for a post-industrial whole foods diet full of grains, legumes and dairy - just not their industrialised versions:
Over the last century, a period far too short for significant genetic adaptation, industrialization has changed radically the way we eat.
Today, the majority of food that typical Americans eat is prepared commercially, either in packages or from restaurants, and refined sugars and fats are universal. These foods are designed to be extremely palatable — so palatable, in fact, they run roughshod over the body's normal satiety signals and encourage overeating. The top six calorie sources in the U.S. diet today are grain-based desserts (cake, cookies, etc.), yeast breads, chicken-based dishes, sweetened beverages, pizza and alcoholic beverages. These are a far cry from the foods that sustained our ancestors.
In short, paleolithic diet is simply low carb, low sugar whole foods - a prescription and dietary recommendation around for a long time:
"People who significantly increase the amount of vegetables, fish, nuts, lean meats and fresh fruits in their diet, and who reduce their grain, dairy, and legume intake have lower blood sugars, usually lose weight, and usually have more energy," says Dr. C. Vicky Beer, a local physician who uses the Paleo diet in her clinical practice. "Every patient I have ever had with diabetes who has adhered to the Paleo diet for most of the time has experienced dramatic results," she adds.