Chess, like olympic sports, is weirdly nationalistic and a source of national pride. I'm not much of a history expert, but I suspect that was largely caused by the soviet union deciding that they would be the best at it.

As for not using his name, try and write the headline both mentioning his name, and his age. It's just clunky.

One reason to do that is to make it accessible for your reader. They hopefully have heard of Iran, they can "understand" the headline. Even for people who know of the situation sometimes players get a preceding nationality because then you don't need to remember the names to follow along with who is who.

If anything it's nice to see some good press for Iran on an American site. I fully expect him to be retconned as "French teen" or "American teen" or whatever else once he gets his new federation.