As a fan of the NBA, I think some things need to be made clear:
1) As previously mentioned, Donald Sterling owns a franchise. He is 1/30 of the league, and as such he can't be allowed to torpedo it. Also, the NBA owner's constitution includes a process for forcing an owner to sell their team, and having the league step in to deal with a team is not uncommon. MLB stepped in to deal with the McCourt-Dodgers situation, and the NBA bought the New Orleans Pelicans from George Shinn and his co-owner, most likely due to their finances and behind-the-scenes sexual harassment case and desire to move the team from New Orleans to Oklahoma City.
2) This situation is not being played out in a court of law. Whether the audio recordings were done illegally or not, as soon as they became public, the NBA had to do something about it. While Sterling is free to have his own opinions about race, despicable though they might be, he's not free from public backlash or business ramifications.
3) Many sources have stated that the players were ready to boycott games if Sterling wasn't dealt with. If this had occurred, and the NBA season ended with no champion for the first time in its history, it would have had a devastating effect on the NBA's financial future a la the 1994 MLB lockout. While I often bristle at the immediate call to fire people when a story like this drops, I also sympathize with the players here. If you're an athlete working for Donald Sterling, not only do you now know that your owner is a racist, but also that you've been putting money in his pockets the entire time you've played for him. So not only does the NBA lose it's playoffs, it's a possibility that the following season would have been effected by a lockout until Sterling was forced out. Lost revenue would have severely hurt small-market teams, and the Clippers franchise would have been toast, since no black player would be willing to play for them, and no other player would want to be seen as a racist for choosing to play for the team. The choice to force Sterling to sell (it's not like he won't be financially compensated for the team) was and is the NBA's ONLY option, since letting him keep the team and forcing a player walk-out would have been seen by the public as the NBA supporting a racist old billionaire instead of its players and fans.
Any Southern California sports fan has known for decades that Donald Sterling is human scum. I have a hard time feeling sorry for a guy who is going to lose his NBA franchise due to his own egotism and rampant stupidity.