Illegal to do what? Make unsubstantiated claims to the public? A lot of people should be in jail then.
The whole lawsuit is a joke. If it was illegal they wouldn't go after him with this shit not worthy of being written on a handkerchief. They'd raise criminal charges.
It is illegal, the justice department is investigating. The previous tweets about burning short sellers might come into play. It is more difficult to prove in criminal court. But most people will admit, it is highly likely that tweet had a specific purpose to burn short sellers. Hopefully there isn't emails that get subpoena'd that can prove it.
It is 100% illegal to release any statements trying to produce a move in equities prices.