Bottom line: Musk is has no grounds to sue current or former employees for talking to the press under NDA. The only thing he can do is fire existing employees who are found talking to the press - something they are probably looking forward to at this point as Musk spins Twitter into an early grave.
I believe- duh- that Elon is giving a message to his employees that there will be consequences for talking to the press about inside info. They will be canned for starters. And you can deal with Elon's lawyers after that. Some of the issues that are so tidy to you may cost them hundreds of thousands in legal fees and a miserable three years just to have dismissed or settled out of court.
Message to Elon's employees. Smarten up or quit. Staying to sabotage the company is not the smartest way to go.