Steve, I think you might want to reconsider your interpretation of the word “Zion” as it pertains to the tribe of Zebulon. Zion means fishing, fishery or hunting (for fish) I don’t think it has anything to do with the sex trade.
THE TRIBE OF ZEBULON: RECLAIMERS OF THE SEA
Source: Hitchcock’s Bible Names Dictionary (late 1800’s)
Zidon, hunting; fishing; venison
on the eastern coast of the Mediterranean Sea,
less than twenty English miles to the north of Tyre.
Its Hebrew name, Tsidon , signifies fishing or fishery.
Smith’s Bible Dictionary
I’m not sure I understand your point about “Zion” as that word is not vital to my book’s discussion of Zebulon’s prophesied characteristics. Only “Zidon,” the Phoenician city, is mentioned in Gen. 49:13’s prophecy. I checked five Bible translations and all indicate Zidon (or Sidon) is referenced, not Zion. This prophecy indicates that latter-day Zebulon will have something about it that has a parallel to the ancient Phoenician city. The word “border” can include the “thigh” or genital region as this word is used in Daniel 2:32 for this region of the body. The ancient Sidonians practiced the fertility rites of Baal worship so their city was very tolerant of sexual immorality. So is modern Holland. This aspect of the prophecy about Zebulon is admittedly cryptic, but so far I haven’t seen a better alternative explanation. Modern Holland is nowhere near the ancient city of Sidon, so the prophecy has to be discussing something about the culture of ancient Sidon.