You can be a good president by hiding in your office and approving good policy made by your excellent team, but you can’t become president by doing those things, especially when you’re down. The nominee needs to be able to be coherent in public a lot, doubly so after having what appears to be a very public senior moment. People who have been around old people know that a few good days doesn’t mean their loved one is better, it just means they were good days.