If anybody ever fit the bill for the 25th taterhead did.
The flaw in the 25th amendment is that it apparently wasn't intended for a permanently incapacitated President. The 25th amendment has no provisions for vacating the office of the President.
If Biden were removed from his duties (not removed from office) and Harris made Acting President, Biden would still occupy the White House residence and Harris would have to commute to the Oval Office for the rest of Biden's term.
A permanently incapacitated President would have to voluntarily resign the office before the Acting President can become the full President and move into the White House. I can't see Doctor Jill letting that happen if she can legally hold onto the trappings of the office. She would technically still be the First Lady while Harris was Acting President.
It would have been quite the spectacle if Harris and the Cabinet invoked the 25th amendment to take control of the Oval Office, while Biden still roamed the halls in his pajamas until January 20, 2025.
-PJ