The greeks have a weird relationship with their owl population, they love them I mean the owls of Athens driving off invading armies thing has actually happened a few times.
When sparta attacked, that one by the way saved the city from being sacked, when the Turks invaded which prevented them from being conqured by the ottoman empire. Saved the entire balkans from that fate from what I read. It was a crucial battle, but while Athens loves owls the rest of the country kind of resents the capital, and eating owls was initially done as a form of protest against the capital, until it just became a thing. The fact that the Greeks have a much higher population of stray owls probally has some thing to do with it too.
As for spiting the turks, their national bird is the falcon not the owl so I don't get why eating owls would be done to spite the turks.