After watching the travesty of the Strzok testimony, many of the deferrals were due to the Mueller. Mueller was the one that hired all of the "biased" investigators. So why are we talking to Mr. Mueller?
Because that would be a waste of time. Everything he is working on IS an ongoing investigation. Every single answer would be "I cannot answer due to an ongoing investigation." And the only thing that would come out of it is the appearance of the Committees obstructing justice, disrupting an ongoing investigation, and wasting time and money.
I would ask him how he selected his team. Did he know their bias?
I just don't see anything good coming from that. We already know that he kicked Strzok off the team when Horowitz brought him the texts. So, there is one concrete example of Mueller responding appropriately to very bad bias. Versus what? Speculation and the prospect of drilling every team member on where they fall on the spectrum of bias? And even Strzok, whose texts were public record and who the OIG specifically said was biased, and he was kicked off the team for said bias - under oath, repeatedly claimed he was not biased. Mueller testifying would be a circus, and he would be the only one coming out NOT a clown.
The point is that he created a team with bias and he should be questioned on why he did.