He accomplished both, refusing to engage in any response that would lead him to read from his report or to give a clear sound bite (other than the exoneration matter) that would have a long shelf life.
At the morning session he appeared old and a bit out of it. But if you listened closely, he followed every question and responded to them well with precision. He may have said “not in my purview” or “not in my jurisdiction” or whatever but that wasn’t him dodging questions, it was him doing as he said he would – sticking within the four corners of his report and his mandate.
At times he couldn’t hear the question or identify from whom it was coming but if you’ve ever been in Congressional hearing room, you’d recognize that challenge, especially a hearing as crowded as these were.
He seemed more engaged in the second session, getting his sea legs, but he said nothing he didn’t want to say all day as a way of sticking to his role as an investigator, not a decision maker.
His entire day was summed up in the first 10 minutes of the first hearing when House Judiciary Chairman Nadler asked precise yes or no questions and Mueller was able to state why weeks ago he challenged Attorney General Bill Barr's announcement of the investigation's conclusions. Barr had said the investigation turned up no wrongdoing by Trump, which turned into Trump’s “no collusion, no obstruction” mantra.
Mueller clearly said his report did not exonerate the President. With that, it was truly "mission accomplished" for Mueller.
With that, you probably could have skipped the next several hours of questioning.
So, through that statement, through his avoiding, as requested a couple of times, reading from his report and by not offering up a sound bite, he won’t become the poster boy for the next election but he also did what Bob Mueller does – stating what his investigation demonstrated in clear terms: It did not clear the President of wrong doing. Nor did it convict him. He just reported the facts, ma'am, and followed Justice Department policy that a sitting President cannot be indicted.
He is the model G-man, and he continued that reputation today.