They have plenty of capacity @ 7 & 8 west so no real need of more back up here,
Other possibilities are 4 west & 5 west,
5 west is very low on fuel & Eutelsat 5 west B is a late launch now 4 months away from launch 6 months to serviceable operation,
4 west has limited capacity frequency due to the launch failure of Amos 6 in 2016, By leasing AsiaSat-8 now called Amos-7 only partially solved the problem of the Amos 6 launch, So extra back up is needed here.
The spacecraft has been up there for close on 16 years, so it might be close to empty. Moving west might be a fuel saving exercise, letting her go right round the planet for very little expenditure. All it takes is a bit more time.