My rush to judgement on this failure is there is a material inclusion not properly detected initiating a premature fatigue crack that precipitated the front falling off. Having learned from Dr. Hoeppner that this strategic part will have a fault tolerant material, the crack could grow quite large prior to failure. This would result in an AD requiring inspections at intervals where it is felt any crack will be discovered prior to becoming critical size that will result in the front falling off.
I'm not saying that your judgement is wrong, but considering the fracture toughness of a titanium fan disk you need a "huge" detectable defect to have progressed to start-stop cyclic failure this early in life.
Other possibilities are still open and we as readers have no new facts to go on.
I'm waiting for a hint on the RPM in the last sec trace and better pics of the attachments.