If Biden wins, he won't be making a lot of decisions because he can't think straight due to dementia, and in the unlikely event that he puts his foot down about something, the controlled media will suddenly notice that he's senile and demand he be removed. So he'd be the maximum puppet, the rubber stamp in chief. amirite?
[From Wikipedia] A rubber stamp, as a political metaphor, refers to a person or institution with considerable de jure power but little de facto power; one that rarely or never disagrees with more powerful organs.
In essence, the term is meant to convey an endorsement without careful thought or personal investment in the outcome, especially since it is usually expected as the stamper's duty to do so.
Many legislatures of authoritarian and totalitarian countries are considered as rubber stamps, such as communist parliaments like the Chinese National People's Congress, or the Italian Chamber of Fasces and Corporations during the Fascist regime, or the German Reichstag under Hitler .