Doormen are hard to get around. Fat bouncers typically have some muscle mass, and are just lard asses (think the fat kid on a high school football team, still fat but has muscle mass) the size of land whales. It's also awkward to try to fight someone with that build because they just try to bear hug you. It's probably because getting super-swole guys as bouncers isn't realistic because it costs too much and they have better shit to do.