Aside from my exaggerations on Tarzan....Plastic Surgeons are immune to dementia?
Not only could he not remember names, from the footage shown he also apparently needed constant reminding of what the plan was, what he was supposed to do, who to vote for, etc. There were comments made referring to him as the senile old guy, beyond aphasia. Obviously those were other players comments and not expert opinion.
Again, it could all be an act or editing of the show, but from the footage it does appear that he has some mental hang ups, is often lost and awkward. Perhaps it is all part of the master plan.