Interesting theory. As for time to dig up dirt, what cannot be dug up can be made up.
I believe in order to replace Biden, he would have to be impeached. Is there enough time for this process? What interests me more is who would replace him? Seems to me if Biden were impeached, VP Kamala Harris would replace him according to the 25th Amendment of the Constitution. Kamala Harris would not automatically be the Democratic nominee for 2024. Depending on when this happed Bidens' replacement would be nominated during the Democratic Convention in August.
He would not need to be impeached if they convinced him to step down. If this happened before the convention they can choose anyone they want. It doesn't have to be Harris. I'm guessing they would choose Gavin Newsom.