Unprotected speech generally can only be restricted after a finding on the merits that the speech is indeed unprotected. It generally can't be restricted via a temporary restraining order or a preliminary injunction that's just based on a preliminary, quick-and-dirty estimate of whether a crime was violated and whether the speech is therefore constitutionally unprotected.
A discussion of the legal issues involved in the MBTA suit, which are familiar. The Volokh Conspiracy - Temporary Restraining Order Against Crime-Facilitating Speech About Security Vulnerabilities: | 
