Bearfoil
I looked at the patent, and read about the feature described to preclude a fire. I can only think it didn't work if this was the system used.
The problem though is in the turbine area as quoted in the corrective action section of the ATSB report: These investigations have led Rolls-Royce to draw two key conclusions. First, as previously announced, the issue is specific to the Trent 900. Second, the failure was confined to a specific component in the turbine area of the engine. This caused an oil fire, which led to the release of the intermediate pressure turbine disc.
On 18 November 2010, Rolls-Royce plc issued a further NMSB 72-AG590 Revision 2, detailing further Trent 900 engine inspections, including for defects in a number of turbine area oil and air feed pipes.
Perhaps the shaft didn't move aft at the rigid coupling spline, but failed at the IPT rotor area?
Turbine D