Holy crap, I actually think I understand some of what happened here. It sounds like someone learned about the Byzantine Empire and got very confused.
The western half of the Roman Empire fell in the 5th century, but the eastern half didn’t collapse until the 15th century. The surviving eastern half has been retroactively named the Byzantine Empire, but when it existed was just called the Roman Empire or the Empire of the Greeks, depending on the year and where you were at. The eastern capital (and Rome had two for a while for administrative purposes, along with two emperors) was Constantinople and it was specifically designed and advertised as a second Rome to justify having a capital there.
I think this guy learned about the Byzantine Empire / Eastern Roman Empire, but not how it relates to the Western Roman Empire. Throw in some assumptions, some logical fallacies, a poor understanding of linguistics and transliteration, and then serve with some conspiratorial thinking on the side and you get the above post.