She makes them money. They get to choose what they think will be the most successful and make them the most money.
A&R at Interscope obviously feel like this is the best single choice after it's success. It's only a promo single (not anymore but) and it's been 1 all over the world for longer than TEOG was.
it's just a promo release run y'all and the first single released happens to become the official one...it's no diff than if the second one was the official one released like originally planned.