No, it means they don’t want any further investigation because they know that the main conspirators will be found to be Nancy Pelosi, Milley, the Mayor of DC, the head honchos of the Capitol police (but not necessarily the rank and file), Schumer, Antifa, BLM, etc…
I think - try as they did - they figured out they could never prove in court that these people did what they were accused of.
And yeah...seems like the real instigators were the FBI themselves. I remember reports that day that people like us were confused as to who these people really were who were leading the charge.