If he hadn't he wouldn't have been able to function enough to look at his watch in annoyance at the ceremony.
We mustn't forget what Robert Hur said.
To wit; "Mr. Biden would likely present himself to a jury, as he did during our interview of him, as a sympathetic, well-meaning, elderly man with a poor memory. It would be difficult to convince a jury that they should convict him, by then a former president well into his eighties, of a serious felony that requires a mental state of willfulness.”
Thinks he's normal.