scholar:
Nonsense: If this is really the case then you should be able to tabulate historically when each of those nations served Babylon.
Yes, you're right - that is nonsense. Ironically, the Watch Tower Society actually put it best on this one in Isaiah's Prophecy, volume 1, page 253:
Of course, it would be a fallactious argument from silence to assert that 70 years can only be applied to Judah because specific periods of desolation are not known for every nation (or any particular subset) that was subject to Babylon.True, the island-city of Tyre is not subject to Babylon for a full 70 years, since the Babylonian Empire falls in 539 B.C.E. Evidently, the 70 years represents the period of Babylonia’s greatest domination—when the Babylonian royal dynasty boasts of having lifted its throne even above “the stars of God.” (Isaiah 14:13) Different nations come under that domination at different times. But at the end of 70 years, that domination will crumble.