Placeholder.
Look at it another way. No one other than Mueller has control over the investigation into POTUS.
It would also be rather good if the investigation into Russian activity to influence American politics turned up documents which could be used to show Mueller was following proper protocol in his position and his superiors tried to classify documents in order to make him the fall guy if U1 was ever investigated.
This is why the deep state has been taking a few swings at Mueller. Remember the sexual assault case that came out of nowhere right after Kavanaugh? Remember Posobiec trying to turn focus to his role in the events leading up to 9/11?
They are trying to leverage Mueller. They realize they do not have control and that Mueller is not on their side. They wanted to launch additional investigations, but they can't because Mueller is in the way and stalling for time.
Avalanche diodes appear to be installed wrong in a circuit. They resist the flow of current until such a time as the voltage across the junction reaches a certain critical value, then conduct fully. Much like a spark gap (except without a negative resistance function, that is reserved for tunnel diodes).
Or, maybe he could be likened to an SCR, requiring an external trigger pulse… But notwithstanding….