One theory holds that the investigation that bore his name was mostly run by Democrat subordinates, with Republican Mueller as a Potemkin figurehead. Another is that he has begun to suffer the diminution in mental faculties which sadly accompanies aging in many, but not all, individuals.
A third theory is that Mueller was engaged in an epic cover-up of the swamp critters who began the Russia collusion probe to "get" Trump while knowing it was nonsense as they did so. I'd like to suggest a fourth theory, without claiming it has any greater chance of being accurate.
I ask you to remember (1) that unbidden, Mueller announced some days before meeting the House committees that his testimony would be limited to the content of the 400 page report he'd submitted, and was therefore essentially pointless. And (2) that Mueller asked the DOJ to instruct him to limit his testimony thereto.
In spite of his announced reluctance to testify, the committee chairs persisted. My speculation is that Mueller intentionally made his testimony unsatisfying, boring, low-energy, and bumbling as a way of getting even with Nadler and Schiff for dragging him out to cover old ground. He proved what he predicted: there was no point in his testimony, as he had announced in advance.
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The other DrC disagrees firmly, her view is that no one in the public eye would voluntarily allow him/herself to appear out of it - having "diminished capacity" - as Mueller did. I find her argument persuasive too.
Unless, that is, Mueller fears eventual prosecution by AG Barr and wishes to establish himself as an object of pity, too compromised by infirmity to be charged. I'd estimate he got most of the way there this past week. His bumbling performance could move him from co-conspirator to unindicted co-conspirator - no small thing.
