Saying "Paleo is Stupid" will definitely get more people to read your article. Which is apparently about educating people about saving the planet through food choices. So, educate people, don’t insult them.
Not that I know the mind of the author, but in summary they insult people that wouldn't ever even click the link, while cozying up to those that do.
Many people assume that a Paleo diet primarily consists of meat, but that is not necessarily true. Many Paleo followers promote the consumption of things like yams, sweet potatoes, and some fruits like berries. However, if you listen to someone like Rob Wolff, he regularly promotes the massive consumption of vegetables, roots, and tubers. He even promotes sustainability, supports local farmers, and talks about animal welfare. Even though he recommends not consuming gluten, he doesn't suggest you replace it with gluten free stuff. He goes one step further and suggests completely eliminating grains (e.g., wheat, rice, oats), which are a staple in vegetarian and vegan dies.
A lot of people fail to realize or accept that many Paleo followers were once vegetarians and even vegans. But eventually, usually after many years, they realized that it wasn't working for them and had to try something different like Paleo.