When it comes to vitamin composition, there is no difference between a bowl of cooked vegetables and vegetables on a pizza. Pizza can be a very good food for people trying to increase their muscle mass. Depending on how it is made and what is on it, it can be composed of complex carbohydrates, vegetables, proteins and healthy fats (which a necessity for a balanced diet, and for testosterone production). Considering the site is "wannabebig.com," I can understand why they may recommend getting your vegetable consumption from pizza.
As for the article itself, I haven't had an opportunity to read it over completely to evaluate the content. But it is important for everyone to research any information you read and to check out the sources of any article you come across. There is a lot of false information out there based on something referred to as "bro-science."
*** bro-science: Information that is incorrect, but is accepted as fact by the general fitness community because of the frequency in which the information is presented as fact. (We see this in the reptile community as well with various issues)