Registered to a leasing company = asset stripping.
Not usually true. Finance leases (where the airline still technically and practically "owns" the aircraft) often use an SPV (special-purpose vehicle) in a tax- (or other-) advantaged country - often required for the financing.
Nothing to do with asset stripping. Especially if the SPV shareholders are the airline... (not saying they are/are not in this case).
Anyway, even if the aircraft was sold/leased back, what's the difference from selling the aircraft outright? Airlines (even/especially QF) do that all the time - you don't expect them to still own it when it's 30 years old?