They are losing their base over Biden's dementia. They are in a pickle; if Biden is removed they get Harris (and neither one of them can handle the message)! Putting Obama out front reassures their masses that Obama has been at work behind the scenes the whole time, and Harris remains VP. Now if the staff can only string Biden along a bit longer, Obama will continue to make timely, vocal appearances to bring calm to the crazies as directed by his higher-ups.
The 300 pound gorilla in the room is that if they remove Biden it lends that much more legitimacy to the claim that the election was stolen. How many Presidents have either resigned or been removed?