Tower cranes are fairly fixed in how far they can reach with loads. They also prevent other large and mobile cranes from working in close vicinity and would be difficult to use when affixing all the different sized pieces that make up the non-uniform mountain shapes. Combining both approaches actually is more effective and reduces final completion time.
It'll be interesting how they choose to work on the upper areas of the rockwork. Shotcrete is an obvious choice, but there may be limits in how high the equipment can service. They may be forced to use the tower cranes to lift material to the higher levels and have the material manually applied.