There are a number of automatic penalties in canon law, and there are Popes who have issued decrees imposing automatic penalties.
I am pointing out the simple fact that these are MEANINGLESS. The very fact that the penalties are “automatic” means that that the so-called penalty is imposed by—NOBODY.
The same is true in the case of a heretic who is “automatically” not Pope.
Go to Rome. Snatch Bergoglio’s beanie off his head, and proclaim to the crowd that he is not Pope.
SEE WHAT HAPPENS NEXT.
Except that is not true. A manifest heretic ceases to be pope ipso facto not because of a penalty incurred via canon law, but because of the penalty incurred via divine law.