I think then commissioner Bart Giamatti knew full well he bet on his own team and also bet against his own team. While Rose did admit to betting on his own team he never admitted to betting against them. Perhaps if he had shown contrition and admitted to his wrong doings years ago he might have been shown some leniency. Alas, he never did.
Joe Jackson is a bit different and definitely some grey area there, but that is another story.