NBA should void the contract.
Whether or not Jordan "signed" it is not the issue. This is clear circumvention of the established CBA and salary cap.
The league is lucky that Cuban simply let most of this matter go. Cuban is a media force now to be reckoned with , and in bed business wise with a lot of entities that deal with the league and the networks that broadcast the games. Cuban could have simply leveraged all that to bear against the NBA.
My take is Ballmer spent 2 billion, so this is his "mulligan" ( the league could have hit the Clippers much worse, if this was the NFL, the league would have gone pure scorched Earth here) Cuban simply weighed out adding to the embarrassment of the league administration and the ripple into the coming labor war when the net change would be none.
Karma is coming for the Clippers here. Journalist Charles Pierce said it best, you might hate Donald Sterling, you might loathe his views, but part and parcel, fundamentally did the NBA just strip a team and sell it for 2 billion to increase valuation of all NBA teams under the pretext of being offended by a person they tolerated for 20 years knowing who and what he was, trampling the concept of free speech, even if repugnant, along with it.
I don't hate the Clippers as much as the Patriots, but it's pretty damn close.
Fck Donald Sterling and the pretext of being offended after being overpaid by 1.5 billion dollars...
The Clippers punishment might be o the officiating during the playoffs.

Pretty obvious what they did. And it probably just isn't them. I mean any player going to big market teams (especially) can have "perks" given to them to sign (beyond the contracts numbers).
This should be looked into more. To even be caught when it is so easy to circumvent is suspect!
I think this is basically a makeup call for how the Clippers broke the spirit of the law and fucked the Mavs over. Yeah its likely other teams do this and the league turns a blind eye to it. However, if the Clippers are going to break tradition to keep DJ the league can break tradition and fine them them for something they usually just ignore.