I think people are misunderstanding something. Man-gi isn't all fat. While the body builder dude is around 5-8% body fat, man-gi is around 20-25% body fat with the same amount of muscle as the former.
Moreover, the only reason the body builder could beat hobin was due to the size difference. But man-gi is a best in class fighter. The body builder has no chance against him. It's going to be a beatdown like how moonsung beat up ppakgo