Bahamut in Coil

[Kaname1304]

My guess is that clearing the Coil Turns is having to side effect to slowly "re-contruct" him.

Basically think as if each Coil Turn was a different lock on the Bahamut reconstruction/reform/whateveryouwanttocallit and you are the key to unlock each step, one by one, despite still thinking that you're exploring and eventually trying to put an end to a problem that you'll eventually be the one to cause.