The article has a lot of flaws to it - but also a lot of truth. It starts out talking about how many calories per acre corn produces and how sad that most of it isn’t converted into human food. That’s fine and good. But then it does a lot of hand waving about organic farming being better and more diverse crops being better.
There isn’t any mention about how many more acres of grass or other crops it takes to raise a pound of beef or chicken. Yes - the conversion ratio from corn to meat might be really crappy - but I suspect that other crops will result in requiring more acres of land to raise the meat.