Well, he's banned, so he can't participate in the league, even though he still owns the team, he can't really do anything but sell them because he literally cannot do anything without being in violation of his banning. It's a power play, the only measure of revenge he can take is sit on the team as long as he can without selling.
The league still owns the team, the owners are just like individual babysitters that keep up the upkeep while the league is off doing better things.