If the FBI found NO evidence of lying why was Flynn charged?
Once charged he would be "expected to cooperate" with Mueller. I think that is exactly what he did. He knew where a lot of the corruption was and helped Mueller prosecute it.
So I believe Mueller is NOT a black hat. I believe Mueller is actually doing his job and will be rewarded for it with leniency given to him for his part of the U1 and other coverups. He's is as Q said…ex Marine.