Forget it. This will play out, die down if it's bullshyt or actually sink Biden if it's credible. It is what it is.
It can play out, even if it damages Biden a bit, cause at the end of the day, Trump has done worse.
What the Bernie supporters pushing this narrative like there is no tomorrow don't understand, is that negative campaign drives down the frontrunners numbers , but it can also be a poison pill to the person seen as leading the narrative. So by the small chance these accusations are true and Bernie becomes the nominee, good luck uniting the party.