Great point Stubborn. What your comment reveals is that there is a difference between someone who has been baptized in the Church, or received into the Church after baptism, and a person that has never been a Catholic. If a person that has been received into the Church falls into heresy, all he has to do is confess it to be reconciled with the Church. The only exception is one who was declared a heretic by the Church. In that case, he would also need to have the declaration lifted.
As long as the Catholic remains in external union with the Church, he remains a true member of the Church (one opinion), or at least a member in appearance only (second opinion). Those who hold the second opinion (e.g., Suarez, Cajetan, Franzeline, John of St. Thomas) admit that being a member in appearance only suffices to hold office in the Church and to retain jurisdiction. The point being, all admit that if a cleric falls into the sin of formal heresy and loses the faith, they will retain their office and jurisdiction as long as they remain externally united to the Church.
Well, this is the dilemma.
The sedes, for obvious reasons, must incorporate "all heretics are non-members" into their doctrine. Yet despite the fact that we often see language in encyclicals etc. which suggests this, there is the above truth which, as such, cannot be denied. Only Catholics, members of the Church can receive the sacrament of penance. Period.
It is because this cannot be denied that like you, I opine the language we read in encyclicals etc. must pertain only to those who have never been Catholic, and also to those formally declared to be a heretic and excommunicated - but even among them there is the exception provided where the danger of death is imminent.
One thing that is certain, is the idea of the Church kicking out a sinner, any sinner, is altogether contrary to the Church's mission and purpose. St. Thomas says the primary purpose of excommunication is medicinal, whereas the sedes' idea of excommunication is primarily punishment.