Lyman, I wish you would consider the fact that turbine discs don't just fail at near-normal rpms, absent some significant manufacturing defect. I point to the eight engines intentionally crashed on 9/11. All the turbine discs, from (I believe) three different manufacturers, remained in one piece after the dust had settled. There are plenty of other accidents available for study in which the impact forces failed to break the turbine discs.
Consider also that the IPT on this engine generates (I'm estimating here) 50,000 shaft horsepower, all of which is delivered to the IPC. If the shafting (drive arm in this case) lets go, it's like tromping on the clutch and accelerator at the same time.
No, the only things that I'm aware to cause disc failure are overspeed, overtemperature, or a fault in the disc (either during forging, machining, or some repair process). For you to propose otherwise for QF32 will take some very serious analysis.