My impression is that the Matthewites have always wanted to make the discussion about grace, but that was not the basis of discussion between the GOC-K and the SiR. The issue of faith was whether heretics were inside or outside the Church, and whether the GOC had authority to anathematize heresy, and on both points the SiR conceded and agreed to join with us. The question of grace was outside the scope of the discussion.
Of course the ecumenists would be highly unlikely to join us even if we did convene a Major Synod to condemn ecumenism, sergianism and the new calendar. But the point is not to convince dedicated ecumenists, but those who are currently in the ecumenist churches and who are uncomfortable with developments but still hesitant to make the leap to the GOC. If all GOCs speak with a united voice on this issue, we can hope to convince many more to come.
If the united GOCs of Greece, Romania, Russia and Bulgaria came together and made a clear statement on the grace issue, would that satisfy the GOC-S?