Do 69% of Georgians really live in the Atlanta metro area? I think it’s just slightly over 50%.
65% of Georgia lived in the
ATL media market in 2010; I'm sure that number has grown by at least 2-3 percentage points since (plus a lot of rural downstate doesn't produce turnout matching its population), so if they're using media markets as (quasi)delineators, then it's accurate.
EDIT: yeah, after closer inspection, I'm pretty sure PPP's regional categories line up as such (they consolidated Columbus + all the other partial media markets into "Other"):