It's not just about Biden. It's a much larger issue than that.
They see an old/weak current President, a weak Congress filled with kooky conspiracy theorists, a fractured American public where half believe the President is illegitimate, an ex President calling Putin a genius, a far left and right press/media that pits Americans against one another daily, and social media that fuels it all.
Putin's a lot of things but stupid is not one. He watched our American citizens attacking the US Capitol. He watched our cities burned and looted by BLM.
He smells blood in the water and it's not just Biden's blood he smells.