The really confusing thing about the post-election lame-duck period of the Trump Administration is why they did a bunch of last minute things, without any apparently awareness that stuff like this could happen.
I guess it is possible that they believed their own bullshit and did not think that Biden could come in and remove their last-minute appointees and cancel their 11th hour arms deals. But if that was the case, why did they rush through with these deals and appointments in the last minute? There was no reason to rush unless their time was running out. But if their time was running out, all those rushed accomplishments weren't really going to last long enough to make any difference.