[Destro]

the average person in the Eastern Empire right down to the end called themselves "Romaioi". The Orthodox church considers itself the legate and defender of Rome of ROMIOSINI.

[FBDinNJ]

The average citizen in the Eastern Empire could have called themselves whatever they wanted to for all I care. But the fact that they considered themselves Roman was part of the problem, which led to the downfall of Roman Imperial power. This situation with an ever expanding group of people who held Roman citizenship eventually led to people from 'barbaria' attaining citizenship. This situation eventually led to Germanic tribes crossing the Rhine and eventually the sack of Rome and the downfall of the Western Empire.

Alright lets assume your premise is true that the Orthodox church considers itself the legate and defender of Rome. Just for the sake of argument lets say that's true.

They clearly didn't do a decent job then did they? Rome was not defended at all by her Eastern citizens, who quickly even revolted against the control of the Eastern Emperor as a result of the Monophysite heresy. These same people who betrayed the West eventually betrayed the east and helped the Islamic armies conquer formerly Christian lands. What kind of defense is that?