The texts you cited admit that people can know about a heresy (presuming it is heresy) without contradicting the notion that it still can remain occult. You're too myopic on this. First, you're equivocating on the term 'public' as it relates to a heretic among Catholics in contradistinction to a 'public' heretic as it relates to being associated to an heretical body. Secondly, you're not taking into account the entirety of the Church legislation. If you are correct, that upon the mere fact that a few people know about the heresy, they are absolutely cut off from membership, then there is absolutely no rational basis for authority to admonish an errant cleric. Even St. Paul states that one ought to avoid a heretic after the second admonition. That is a simple restatement of the legislative process of the Church. Finally, you are confusing the Divine sentence with the Church's judgment. In the abstract and in God's sight, the errant cleric may be entirely cut off from the Church, but the Church judges according to the external forum because it is an external society. This is how all of her judgments must necessarily proceed. And this in turn goes back to the notion of the basic requirements for membership in the Church.