No, that does not follow. Biden can be fit to be president right now, but (1) not able to campaign, which requires a different skill set, and (2) not certain to remain fit until January of 2029, or even 2026. He's clearly showing a cognitive slow-down. At this time, he is possibly (even probably, I think) still able to think WELL, but there's a fairly high likelihood that any 82 year old will start losing judgment capacity before age 86, and especially if he is beginning to be impaired in other ways.