bear
The bits that went "uncounted" came from the hub, as well. The fracture (Tear?) in the disc, is remarkably free of random trail, it is "straight". To say again, the failure seems from the Photographic Evidence to have started at the Hub. If the disc failed prior, there would be evidence of "Wobble" and chaotic fracture, not a clean line. This is consistent with DevX' statement that the fire was involved at the hub, and bearing. If the Titanium Disc had relaxed from heat, and remained attached while the Hub was "Failing", the disc damage would have a completely 'duff-erent' signature, imo.
This is what the available evidence says to me.
Forgive me, but I do not recognise some of your terminology.
I understand the most plausible failure scenario is an oil fire leading to shaft disconnect and disc overspeed to tri-hub burst. Are you suggesting that there is the possibility of some kind of fatigue failure in an area of disc unconnected with the hub?
Note that the the term 'disc' includes the whole of the component ie hub, diaphragm and rim. It is a single component.
And I am surprised to learn that the IP turbine disc is titanium, but I may not be as current in metallurgical matters as you are.
Finally, I think you should be aware that a number of excellent people will be working very hard on this problem, at RR and the various regulators, as would have been the case had it have been anyone else's engine. I do not think we should be questioning their integrity at this time or mocking their efforts.