Perhaps rather than an abrupt about-face at 80 years old, you’re simply incorrect about Biden’s “history.”
He was right about schools. We lost a generation of black educators due to the way desegregation was handled nationwide. Biden accurately commented on this. We could have done better, which is literally what he was arguing for.
I actually learned of this fact tangentially, through an old episode of Revisionist History. His campaign ignored it because it’s safer to ignore than to trust people to understand nuance. Sound campaign move, but plays to a lie, fundamentally.