if they ghave threaten to deny your case after you iled you law suit, that is some you should submitt to the court, but denying your case due to the lack of name check completion, as you can see_if they ever get the ball to do that_ would very easy to defeat, because what they doing is ingnoring the lagal basis on which you have file the suit, 1447(b), which give them only 120 day, and they are obligate by the statue to finsih their investigation in this period.
but lets remember that as long as your case is pending , they can not make any decision about your case period, but they can ask the court to make that decision,which mean that teh cour have either order them to make a decision the judge see appropriate, or at least the judge have to agree on any decion the want to make
so i think you are save from any adverse decision they want to make in your case, because they have to justfy to the court first, the judge have to agree to it, which very unlikely, considering the 120 day, and considereing the whole problem is them and FBI not finishing the work they need to do.