That is the main weakness of that study, that the main direct technical argument I just sort of brushed off. So today I want to get into that more. Then I will go back and edit that older post to include a link to this one.
In the Greek this term is "Megale Polis". This phrase isn't used in any other books of The Bible, only Revelation. But it's general Greek usage does not at all suggest it is a term that can apply to only one single city. In fact in Greece there were 40 places called "Megale Polis". The only time it's used in a sense of being unique to only one city was the city that was actually named that, (Megalopolis, founded in 371 BC) rather then it being only a title of a city. And I don't think anyone thinks Revelation is talking about Megalopolis.
In Chapter 11 the term is used of current terrestrial Jerusalem, and in 21 is used for New Jerusalem. In Chapters 14, 17 and 18 it is indisputably used of Babylon.
Proof that the book intends to apply that term to more then one city is in chapter 16 starting in verse 17, when the Seventh Bowl of God's Wrath is poured out.
And the seventh angel poured out his vial into the air; and there came a great voice out of the temple of heaven, from the throne, saying, It is done. And there were voices, and thunders, and lightnings; and there was a great earthquake, such as was not since men were upon the earth, so mighty an earthquake, and so great.
And the great city was divided into three parts, and the cities of the nations fell: and great Babylon came in remembrance before God, to give unto her the cup of the wine of the fierceness of his wrath.
And every island fled away, and the mountains were not found. And there fell upon men a great hail out of heaven, every stone about the weight of a talent: and men blasphemed God because of the plague of the hail; for the plague thereof was exceeding great.The middle Paragraph above is verse 19. It makes little grammatical and no narrative sense for the Great City and Babylon to be the same city in that context. The Great City was just judged, and now after that is done God is turning his attention to Babylon, setting the stage for the next two chapters.
People who play fast and lose with the Chronology of Revelation may try to argue that 17 and 18 are merely describing in more detail what happened in 16:19. Besides that simply not fitting the grammar of what the text says, Revelation 18 foretells Babylon ceasing to be a City at all, that land to never be inhabited again. Not at all the same thing as being divided into three parts, but rather mutually exclusive.
I think the Great City being divided into three parts is Jerusalem, it fits Jerusalem's history perfectly.
I'd bet that there are Historicists saying this was fulfilled already by modern Jerusalem's division into "Quarters" because calling them "quarters" is silly when the Armenian quarter is so small and the Armenians are Christians. What it was was a dividing of Jerusalem between the 3 major Religions that consider it sacred. But that would not be a truly literal fulfillment of the prophecy, Revelation is talking about a physical division, not man made borders.
The Seventh Bowl Earthquake is ultimately a World Wide event, but it's relevance to Jerusalem I think corresponds to Zechariah 14:4. As that Earthquake like this one follows the reference to Armageddon.
The River that will flow from Ezekiel's Temple in Shiloh will at some point split into two rivers, one emptying into the Mediterranean and the other into the Dead Sea. It could be the same cracks in the Earth that divide Jerusalem in three are also what causes the River to become two rivers.
Thus Revelation 16:19 is proof that Mystery Babylon is NOT Jerusalem. More evidence against Babylon being anything but a City in Mesopotamia can be found Here and Here.