And here's a reminder for all you budding constitutional law scholars out there:
Donald Sterling's banishment from the NBA is not a First Amendment issue. Mr. Sterling is not being prosecuted by any government agency for his words, as ill-chosen, hateful, embarrassing or stupid as they might have been. He is free to say as many dumb-ass racist things as he'd like, without fear that they will land him in jail. Ergo, his First Amendment rights are not being infringed.
What is happening is that his business partners in the cartel known as the NBA have decided that he is bad for business, seeing as a significant portion of both their fan/merchandising base and player base is African-American and thus likely to have a dim view of an NBA that tolerates Donald Sterling any longer. Dim views tend to translate into reduced cash flow, which led Sterling's business partners and the cartel to which he has voluntarily belonged for three decades to say "get this asshole out of here before he kills the golden goose."
In other words, capitalism. He's affecting the bottom line, so get him out of here. That is entirely within their rights based on the NBA constitution that all owners are signatory parties to. They are not seizing any of Sterling's assets, nor are they acting outside of the bounds of the agreement to which all owners are signatory. Sterling is being kicked out of a voluntary business association with a billion dollar sale price as his consolation prize.
So: to sum up.
Not being prevented from saying racist things, just being kicked out of the private business group he belongs to because saying racist things where people can hear them is bad for business. No constitutional rights infringed, no laws broken, nothing personal, strictly business.
It's the smart play. And when it comes to Donald Sterling, Adam Silver is always smarter.