Respectfully, your logic is circular. Baseball could lift his lifetime suspension at any time. If Rose played for the Boston Red Sox or the New York Yankees, he would’ve been enshrined 20 years ago.
Baseball is not going to do that. Pete Rose was suspended because he broke Rule 21D:
Any player, umpire, or Club or League official or employee, who shall bet any sum whatsoever upon any baseball game in connection with which the bettor has a duty to perform, shall be declared permanently ineligible.
Rose accepted the punishment for betting as a Club official (manager) with "a duty to perform."