Basically, this is an expanded version of the protection against prior restraint. Often there will be pre-emptive strikes because someone is digging where you don't want them to look, they're asking the wrong question, they're raising challenges internally that aren't accusations or a formal list of undisclosures, but they're putting the wrong topics on the table. You want to act against them before they can become whistle-blowers and trigger their rights.
The law has to cover all the stages at which someone is perceived as a threat for exercising freedom of speech.