Musk has long waged a rhetorical war against shortsellers-investors who borrow shares of Tesla in order to profit if the price drops.
After the now infamous tweet, shares in Tesla sunk over 2% just hours after sending it out on the social platform.
The stock dropped as much as 3.8 per cent as of 9:40 a.m. Friday in NY, after Musk fired off more than a dozen tweets targeting the Securities and Exchange Commission and short sellers the night before.
His crime? An August tweet in which he falsely claimed to have "funding secured" for a buyout of Tesla at $420 a share.
Tesla's board has already been under fire for being too deferential to Musk.
The post risks putting back in play stiffer forms of punishment that the SEC sought last week, including a prohibition on Musk serving as officer of a public company.
"He'll blame the board for taking him out, or the SEC for derailing his genius", Sonnenfeld said. If the settlement is struck down, the SEC would likely move towards enforcement-it's unlikely they would be as lenient in that case.
Separately, a roofing tile product that could collect energy from the sun was justification for buying SolarCity, a company run by Musk and some family members. The settlement was announced on September 29, two days after Musk was charged.
"I think it's the judge being careful", he said.
Nathan "may want to know why Tesla is paying a fine because the CEO doesn't know when to shut up", said Adam Pritchard, a University of MI law professor and former SEC lawyer. Musk responded, again on Twitter, by announcing he would "send Einhorn a box of short shorts to comfort him during this hard time".
Tesla and the SEC declined requests for comment.
Musk agreed to pay a $20m fine and step aside as Tesla's chairman for three years.