The Explanation

 Here's a headline from an article by a respected (they pay him) writer:

Is Biden Just Picking His Cabinet Nominees at Random?

The answer is yes. My explanation is that they're humoring him. As soon as he's inaugurated, he'll be given a "lateral promotion" to "Executive Manager of Policy*", and President Harris will move all her picks in and get down to the business of running the country into her favorite ditch. So you see, it doesn't really matter who Biden picks.

*Terry Pratchett described  a situation in which the devils in Hell ran a coup d'état against an incompetent manager in Hell. They announced that as a reward for his exemplary work, he was being promoted to Policy Manager or some such. He was given a big office with a big desk and a pile of blank sheets of parchment a pen, and 2 slots in the wall marked In and Out. His new job was to write new Policy and put it in the out slot. The same paper shortly came back through the In slot, which he then would mark up and correct and send back Out. He never noticed that the slots were connected or that his office had no doors. He was very happy.