That is incorrect. It is widely accepted that polymyalgia is an autoinflammatory disease. The inflammatory response is a function of the intrinsic immune system. And polymyalgia is commonly referred to, even in peer-reviewed literature, as an autoimmune disease. It is true that it does not appear to be a disease of the adaptive immune system. So, If you are going to be persnickety and insist on a narrow definition of autoimmune as being a disease of the adaptive immune system, it is not an autoimmune disease, but you seem to be out of step with the rest of the world