If he was on the loc 18nm, ATC ZSSS could easily have just vectored him off and let the QR through. There are a lot of hidden unknowns.
Looking at the fuel remaining for both aircrafts with the Juneyao A320 having only 5 minutes more remaining endurance than the QR B777, it was certain that had the Juneyao aircraft gone around, he would have been the next one declaring fuel emergency. Then another aircraft would probably have to give way to him and there would have been a domino effect of maydays from succeeding aircrafts.