"...'A manly man don’t want [pizza] piled high with vegetables!' [...] Cain then explained that a real man would dismiss any pizza contaminated with vegetables as 'a sissy pizza.'"
This is pretty typical gender policing: "manly" men are supposed to want to eat meat, and it is inappropriately feminine ("sissy") for a man to want vegetables, and for that he should be shamed. One can only speculate how Mr. Cain will react to discovering that pizza is, in fact, itself a vegetable. I hope he doesn't doubt his manhood as much as he evidently doubts mine.