> I don't see any problem here.
The Hollywood Blacklist, too, was between private corporations and private individuals.
I think that in both cases folks had a right to act as they did, but I think one can also argue that they were wrong to do so. What's harder IMHO to argue is that one was right but the other wrong.
I don't see any problem here. This is a conflict between two corporations (the NBA and whatever holding corporation Sterling used to own the Clippers) where one (NBA) decided to terminate the relationship.
As a libertarian, how can you not agree? If freedom of associate is sacrosanct, as you state, then isn't this the NBA choosing not to associate with Sterling? He can seek redress from the courts (which he did, case still pending) if he wasn't happy.