I see a similar scenario that I think the Dem policy makers may have hatched up some time ago. They wanted a President that is full throttle liberal/Socialist and Biden is not that person rather Harris fits the bill so put her behind Biden who was a choice of the mainstream Democrats and get him elected knowing full well they would have options to see him leave office via foreign money scandals or being mentally incompetent.
Harris would never get elected but she would be the next in line for the office. Biden probably couldn’t get elected by popular vote so the critical states were doctored with false ballots to get Biden in and the plan would be in place for one hell of a ride with Harris because she would support anything that was socialistic inclined. She would be a sponge for all the liberal policies.
Biden’s days in office are numbered but may run as far as half term giving Harris face time to the public and allow them to get familiar with her persona.