Just had a thought: if Biden were to offer Trump a pardon for the insurrection, and Trump were to accept it, that would legally count as a confession of guilt. Since the 14th amendment clause is not a part of the criminal statutes, and with the precedent that it still applied to the Confederates that Andrew Johnson had pardoned, Trump accepting that pardon would be enough to activate it and prevent him from holding office again.

Seems fitting, seeing as Trump rallied a mob waving Confederate flags to storm the Capitol.