The destruction of Babylon is not only prophesied in Revelation, see for example Isaiah 13. The prophecies about Babylon seem to include a number of Babylon types, although the final calamitous destruction will take place once, to the “real” Babylon. I think he is saying that Jerusalem was a type of Babylon and therefore suffered a type of destruction that it was in no way the destruction that will be suffered by the real Babylon. But his point, how Jerusalem can be considered a type of Babylon, is very interesting and scripturally sound.
“The destruction of Babylon is not only prophesied in Revelation...”
The destruction of “Babylon the Great” is what Revelation talks about, and it makes it pretty clear that it is not talking about the Babylon in Mesopotamia. There are prophecies of the destruction of actual Babylon in the Old Testament, but those were already fulfilled when Revelation was written. That destruction was permanent. There was no Babylon during John’s day, and there still is no Babylon today. Saddam wanted to rebuild it, but he just threw up a tourist attraction in a different spot. Babylon itself is still an uninhabited pile of ruins.
“But his point, how Jerusalem can be considered a type of Babylon, is very interesting and scripturally sound.”
Well, it’s referring to Jerusalem under the name “Babylon the Great”, but actually making prophetic statements that must apply to a real city, and the real inhabitants thereof, so it seems to be a “code word” for the real city of Jerusalem. This version of Jerusalem, the earthly one, is contrasted in Revelation with the heavenly, or “New Jerusalem”, just as the faithful bride of Christ (the church) is contrasted with the unfaithful, adulterous harlot. Go search around the Old Testament for prophecies about adulterous harlots and you may be surprised who God uses that symbol for.