bearfoil:
I lean toward an engine Stall with interruption of N2 gas, the first bang, and having blown through the IPLP, and upset the IT to disintegrate, it exited the case, second bang.
An engine that will not tolerate (mechanically) a high-energy compressor stall WILL NOT withstand all the test regimen in development and certification testing. Whatever failings the Trent 900 might have, I find your thesis to be very far-fetched.
Turbine discs are very stout. The 9/11 crashes demonstrated that; of all eight engines that were destroyed that day, all the turbine discs were pretty much intact. To envision a compressor stall inducing a disc burst is "round the bend".