Vince notoriously does not like bellies.
He makes everybody who doesn't have a flat stomach or abs wear some type of top that covers their stomach. All them guys you named had some type of belly covering top.
That's why Corbin has a top, Omos has a top. Dabba Kato has a whole jacket. Rikishi, Umaga, Yokozuna, they had them high ass belts. Owens already wrestled in a singlet with a shirt, but he probably wouldn't have had a choice anyway.
Kamala might've been like the only one who had his whole belly out, and I think it was because part of his (racist ass) gimmick was that he slapped it for whatever reason.
Otherwise, if they have a stomach, it's like they're told to tuck it in their pants.