Let's go back to the point. The (unrecognised) MOC Archbishop Stefan gave a hate speech against the Bulgarians there.Sadly, the striving for "National Autocephalous Churches" and racism are often found together. "The Church is beyond arbitrary national borders (which, lets face it, have changed innumerable times over the centuries).
Once they feel deeply offended and hated (without any real reason for that), they have the right to protest and to look for an alternative solution!
You have put your finger on an essential truth. I would also say that ethnic pride in multi-national settings can also cause the same problems. The principle that "the Church should be beyond arbitrary national borders" is an ancient and persistent one. One finds it as a pillar of governance in the Roman, Ottoman and Russian Empires. In each instance, one ethnic group, under the guise of this noble non-ethnic organizational principle, lorded it over the other ethnic groups, and even attempted (often violently) to force them to renounce their ethnicity for the self-proclaimed larger "non-ethnicity." We are all familiar with the smoke and mirrors played with Holy Rus and Hellenism. I must admit however that all of this behavior was predictable and in accordance with organizational behavior: standardization occupies at least 80% of management's attention, even in most modern, transformative organizations.
OK, let's get back to reality and we should approach it from the beginning. First, the early church was a loose confederation of churches. After the Church became the partner (and at times tool) of the state, it was standardized and organized to suit the purposes of both the state and church bureaucracies. Par for the course for large states and organizations but I would submit not necessarily in accordance with the Holy Scriptures, the Early Fathers and their practices--that is, an arrangement that was suitable, at best, for the circumstances that the Church found herself in. A precedent for sure but not prescriptive for us.
Second, the main principle of church organization is the Ignation model of "one bishop, surrounded by his priests, deacons, and laity." This ontologically complete church may be as small as one church, several churches in one city, or still larger amounts in a metropolitan area-a diocese.
Third, the Lord Himself tells us to "...go and make disciples of all nations" (Matthew 28:19) and Saint Luke's Book of Acts makes clear that such effort should accommodate the particular ethnic makeup of the target audience--that is in the vernacular (Acts 2) and without any extra requirements (Acts 15).
Just as the Church found herself within the context of empires (and adjusted accordingly), so did She find herself within the context of nations later on (and is still adjusting in certain places). I would submit that neither adjustments are prescriptive, notwithstanding the fact that they are indeed two different precedents. But, so is the very first and truest of Orthodox praxis.