The morals clause is a pretty unstable thing for the NBA to place their hopes on. There's contracts, there's laws and then there's the cost balance of enforcing it.
The NBA's moral clause is shaky if this goes to court because all that has to be brought up is all of the past players that also signed the same clause in their contracts to be brought up as examples of inaction by the NBA. You have to have morals in order for a morals clause to hold up. The NBA has proven in the past they don't really give a shit about morals.
The only way the NBA gets rid of Sterling with as little kick back as possible is money. And that price will be set by Sterling. All that's left to do is find that amount and this goes away.
Morals clauses are discretionary. There's no requirement that they be equally enforced.