FBI is pretty cunning. They put Danchenko on the payroll so that they could justify redacting everything related to him as a "confidential source".
And this is not that long over Danchenko fleeing the country as the FBI was quite certain he was a Russian agent/asset.
So the FBI realizes that all of Clinton's bullshit agitprop was merely routed through Danchenko, because basically he had a Russian name and Russian contacts, and they thought it was very possible he was a spy, but they put him on their payroll and protected him.
FBI got some 'splainin' to do.