The surprising element in the special prosecutor’s reflections on President Biden’s mental faculties was not the content of them, which has been perceptible for years in a politician who in his prime jokingly referred to himself as a “human gaffe machine.” Technically, the president and his supporters are correct that while this state of affairs sharply reduces Mr. Biden’s forensic and debating talents, sharply restricts his exposure to the press, and makes it difficult even for him to manage a teleprompter, there is no evidence that it materially affects his judgment.