Old Engineer
As shearing is the most energy-efficient way to cut thru metal, I am not convinced that the disc fragment would have made much noise going through the wing. You can see the impression of teeth going thru the crossframe web, cut like a die-- is this the trace of the oft-mentioned bevel gear?
I would agree with you on this, partly. However, when that disc broke, it made a BANG just like a test bar failing during tensile testing, only louder.
Note the puncture hole at the top surface of the wing, it corresponds much like the cross-section of the IPT disc. It is hard to say what else came out inside the wing, but I think it isn't the bevel gear, it is too far forward in the engine and it would not appear there is much external damage forward of the HPT rotor.