I saw that video. It made me think of the upcoming case about presidential immunity. A decision in favor of Trump would destroy Biden’s attempt to convict Trump. As a reply to Biden’s taunt, they may decide to ram that one down Biden’s throat sideways.
Maybe the case of presidential immunity was what drove the speech writers to be so blatantly offensive. Make them mad so they rule against immunity in the short sighted view that they don’t want Biden immune. Help Biden win with no one really going to go after him for his crimes