What if Biden’s senility is actually a debate strategy? Trump is notoriously unbeatable in debates. He wiped out 17 Republican competitors and then Hillary with no effort. And now he gets regular practice with a crowd of extremely hostile reporters. How to appear at the debates and not come off as a loser?
One strategy could be to prepare people to see a frail, senile old man. Then, when they see somebody completely with it intellectually, the impression will be a lot stronger than without months of senility rumors.
Voters only remember and care about the last thing they saw a candidate do. This could work. It already kind of did in a debate Biden had with Bernie last Fall.