Cletus, I thought of something else:
Being that dementia isn’t temporary, and the 25A only provides for a temporary solution which is initiated by the POTUS, what constitutional remedy exists for the situation where a president gets increasingly worse dementia.... and isn’t capable of initiating the 25A?
Joe is getting near that condition (if not already there).

:: what constitutional remedy exists for the situation where a president gets increasingly worse ::
None.
We only have Eleanor Roosevelt as a modern day reference.