You assume Trump tweets every time he's unhappy with somebody in the executive branch. I don't make that assumption. And I don't think Trump is happy with his current FBI director, Wray, and I believe he will replace him when the time is right.
And it's not the FBI's, or government's place to warn against people who are committing no crime and who not advocating any violence, for example the Qtards.
I am glad Trump is barring Q stuff at his campaign rally. But that's a far different thing than the FBI warning about non violent free speech.