You go to the trouble to find it and bring it up, the original owner gets it back - US Government, Spain, etc.
With cash-strapped countries everywhere, good luck keeping what they abandoned and you worked and risked your butt to raise.
Perhaps he prefers to bring up Etruscan, Phoenician, Assyrian, and Carthaginian treasures. I doubt that they have the lawyers needed to retrieve "their" sunken treasures.