I say the distinctions are questionable: The New Testament makes no such distinction between false teaching and heresy. When the Apostle Paul tells his disciple Timothy and the various churches to which he wrote not to tolerate false teachers, he did not make a distinction as to whether their false teaching concerned a matter that would someday be included in the Nicene Creed. In fact, the admonition was often to separate from false teachers who promoted immorality (1 Corinthians 5:11, 1 Corinthians 10:8, 2 Corinthians 6:17, Ephesians 5:3). The same is true for other apostles (2 Peter 2:1-10, Jude 3-7).
Heresy has also been defined as any departure from the faith of the Catholic Church, which Vincent of Lerins identified as that which has been believed by the whole church throughout the world, from the beginning, and by all (universality, antiquity, and the consensus of the faithful). Who can disagree that the Episcopal Church has seriously departed from the received faith of the universal and ancient church–and on a matter of ultimate importance: God’s stated will for humankind in the matter of sexual relations and God’s ordained sacrament of Holy Matrimony?
And as to remaining in communion, the New Testament makes no such stipulation. The Apostle Paul does not say, if the body with which you are associated continues in false teaching for a generation, then you (or, more likely, your children) are obliged to separate from it. No, the admonition is that those who are serious about following the way of Christ are either to expel or to separate from false teachers immediately.