If the Germans had managed to win the war and occupy Britain, would it have been OK for them to sell the Cerne Abbas giant, say, to the USA? One presumes that TTT would heartily agree with that deal!
The sculptures were clearly made by Greeks in ancient Greece. Sadly, however, at the time that Lord Elgin "bought" them, Greece was under the control of the Ottomans, basically Turks; that is people who had no feelings necessarily for things Greek.
Now the Greeks are independent and have every right to claim their cultural inheritance that we merely plundered, as we also did in Egypt and elsewhere.
We would be infuriated if a power temporarily ruling us had flogged our 'upstanding' historical figure, I'm sure!
Give the Marbles back; they never belonged to the Ottomans to sell and nor were they ours to buy!