Even if Middle Easterners like Persians are light they still are different from whites because of their language and culture. Look at lighter-skinned hispanics or asians, they might be the same color as whites, but they ain't the same because they identify with being something else. Also 'person of color' is used out here in NYC to mean non-white, kind of replaced or is the politically correct way to say minority.
A persian fool I know gets real offended when black folks think he's white. Personally he don't look too white to me but I could see why a black person might go ahead and classify him as white because he's 'close enough'.