What a ridiculous argument. Remember that the Eastern Orthodox church was essentially created by decree by Constantine, who split the Eastern and Western Roman Empires. That was not exactly popular with the already established ecclesial bodies.
By your logic, you must then consider the Eastern Orthodox church as illegitimate as Protestantism.
The Catholic Church and the Orthodox Church are legitimate churches of Christ. Both have apostolic sucession, even though the Orthodox Church broke away from the true Church, which is the Roman Church, and they share the same sacraments. Protestantism on the otherhand is a heresy.