I'll play devil's advocate here to some extent....
First of all, the NBA can do whatever they want. Frankly, I think Sterling should have been pushed out of the Clippers' ownership structure years ago after his settlement of a housing discrimination suit where he was accused of encouraging his employees not to rent to Black and Hispanic tenants. See here:
http://sports.espn.go.com/nba/news/story?id=4187729On the scale of crappy things Donald Sterling has done in his life like practicing housing discrimination, evicting elderly tenants who were ill, and cheating on his wife, telling his mistress in a private conversation not to post pictures with minorities seems pretty tame in comparison to me, at least in terms of damage done to the victims. Of course, we live in a world today where the outrage industry is active 24/7 and people are always looking to point the finger at someone else and yell "Bad!" in order to feel better about themselves. Call it "Trial by TMZ." That's where were at as a society in 2014.
Also, one last thing- have we just completely skipped over the fact that his mistress actually violated the law by taping their conversations without his knowledge? Is that just okay and fine and dandy nowadays, as long as the scapegoat is rich and easy to hate and the outrage industry is on your side?