Twitter went even further and prevented people from exchanging the story with each other in DMs.
I honestly don't see how you could be comfortable with this, unless you're willing to disregard their actions because they happen to protect the party you agree with at the moment; or because you're presuming that the FBI would never use this relationship to operate in bad faith.
Twitter didn't go to the FBI to ask for verification, the FBI on their own accord decided to take their "intelligence" to Twitter for action that they desired. This is obviously backwards.
If Twitter wants to call up the FBI for verification or for information on a particular subject, tweet, or account because they wanted to investigate.. that would obviously be fine. That is clearly not what is happening here.