Expressed differently, we have been told that the Church could never lose it's "governing body." Churches may be stolen by imposters; thugs may appear to arrogate to themselves buildings, etc.; the Antichrist may set up shop in St. Peters . . . but the true Church with its pope and genuine governing body would go into exile, reduced to a few and a minority, etc. The vision of Fatima, with the pope martyred, shows this.
But we were never told that a pope, duly elected by the cardinals under the guidance of the Holy Ghost in lawful conclave, could be one of the thugs.
That is inconsistent with the guarantee or promise, as relayed to us.