The big problem I see is if he does have Parkinsons, anesthesia will scramble his brain big time. President Pudding Cup vs Vlad the Mad. I see no happy ending.
Confucian Curse: “May Your Life Be Interesting”
In terms of leadership, there is a big difference. Putin has always been a mean, suspicious adult. Biden does not seem to have much in the way of meanness. Putin will be hard to control, Biden not so much. Then the question becomes, who is trying to do the needed control.