> Always strikes me as odd that Biden is somehow both a senile decrepit old man and a criminal mastermind depending on which is most useful at any given moment.

Biden is not a criminal mastermind, and he never was. He changed into a decrepit old man, surrounded by a cabal of people that did not shy away to use the tools of the president's office for their personal gain. We know now that a lot of the president's autopen signatures did not originate from Joe Biden. This group of people also had a general interest in hiding the president's condition.