I would disagree.. the Magisterium teaches that heretics are not in the Church and has never made the exception for occult heretics. That also would destroy the Unity of the Church.
No, that is not what the Magisterium teaches:
Trent's catechism:
"Heretics and schismatics are excluded from the Church, because they have separated from her and belong to her only as deserters belong to the army from which they have deserted." Although they belong to her only as deserters, the catechism says they still belong to her - in spite of their trying to get out of it.
Do you see where the magisterium teaches that heretics belong to her - and how they belong too her? I bolded it for you. If you see and understand this, then you will also see that the magisterium does not teach heretics are not in the Church - they still belong to her.
You need to remember that Christ established the Church to save all men, Our Lord knows that She is our only refuge and is eager to bring sinners into her fold so they can go to heaven, not banish the sinner so as to be sure they go straight to hell. Yet this latter is the attitude sedes consistently portray her as having.
"I say to you, that even so there shall be joy in heaven upon one sinner that doth penance, more than upon ninety-nine just who need not penance."