technically they can say it's greek style if it's dehydrated milk base. if it is made from full fat milk it is 7-12% fat depending on how much it was cooked down. when it had only 0.2% fat to start with by the end it's only 0.4-0.6.

if only the greeks could make "greek yoghurt" like the french make "champagne" and the serbs "schlivovits" then they would have to say 'thick yoghurt' instead like 'sparkling wine' or 'plum brandy'.