It’s not a gaff. It was not a joke. It was clearly an arrogant racist comment by a guy who thinks he is a plantation owner.
It helps to actually watch how he said it
It was another one of his “Look, Fat” moments where he’s being Mr. Tough Guy who wants to take you out back of the school for a beating
Biden _knows_ he is a plantation owner from the plantation owner party.
He just forgot to keep his mouth shut.