Hmm interesting point! But at the same time I disagree that a WLS person wouldn't have a shot. It's pretty common anymore. Besides, the producers are casting for stories above all else. They've cast Little people, those with health conditions, who've had cancer, old people, etc. Anyone with a compelling story is fair game, and a stomach surgery isn't much different than an artificial knee or heart valve repair on a person once when they're out there in the game (less serious than those common examples, actually). We're normal people afterall, its just that we had a surgery at some point in the past, and are now much fitter for it. Some folks even become bona fide endurance athletes. (Contestants are constantly medically supervised anyway, and never alone with the production people all around.)
So its just for fun anyway, assume a colorful character has been brought on board by the producers! They just happen to have say, 5 years of a sleeve under their belt. Any advantage?