To extend the absurdity further. If the President truly believes that if their rival winning the presidency would endanger democracy, it would be the _duty_ of the President to take that action.

This seems like a path towards civil war.

[edit] Thinking about a way out of this mess. Here's a proposal.

Biden asserts that he has this right, writes up a new amendment taking the right away, gives a date by which he will take action if the amendment has not been passed.

(Then he should probably resign for effectively blackmailing the legislative branch)