The SEC has already asked a judge to find Musk in contempt of his settlement after he didn't appear to have cleared the "500k" tweet with the attorney responsible for vetting his tweets.
We've asked Tesla for comment. This isn't the greatest threat Musk faces, since the SEC could suspend him from running Tesla, or ban him outright. However, it certainly adds to the pressure on the executive to rein in his comments, whether it's voluntary or through the courts.
Reporting by Jon Fingas for Engadget.