OK - I have little doubt there was a stall somewhere in the whole sequence, but it wasn't a necessary part of the mechanical failure, but rather it was incidental.
Consider also that the drive arm is much less massive than the disc bore, and was directly in the "blowtorch" zone; the bore would take a lot longer to heat up to the point of failing at 7000-8000 rpm. Thus I submit that it was indeed an overspeed that failed the disc, and that requires the IPT blades to remain more-or-less intact after the drive arm separation. (They could readily disappear when passing through the case etc.)
My reference to the 9/11 engines was simply to point out that normal discs running at normal temperature & rpm do not fail even when horribly abused.
But all this is subject to revision based on more evidence.