I thought the argument was well understood? That the executive, which controls the justice department, instructed the justice department to not prosecute or seek prosecution under that specific part of the law. So technically the law is still the law, but for all practical considerations its no longer the law because a law that can't or isn't enforced can hardly be called law right? Its a rather dubious area with a lot of potential for abuse.
For a comparison though keep in mind all the sheriffs that have refused to enforce magazine capacity laws, its pretty much the same argument.