Its Jet fuel, but not as we know it
Soem Dood I know where you are coming from and I would hope that GC/Mass Spec would have been the first thing that was done for the post incident investigation. Well, possibly the next thing after the traditional Jet tests (Freeze point, Distillation Range, T90, Final Boiling point etc etc.)
If you had access to the results I am willing to bet that what it will show you is that while Chinese Jet fuel is compositionally a bit different to typical kerosene fractions in the west (hence the -52 deg FP) it met specification. The question in my mind long ago ceased to be what caused the fuel starvation, (a couple of us have repeated endlessly our prediction that it was due to fuel stratification caused by unusual temps leading to a mush of ice and wax at inlet) but whether existing Jet specs and automated test methods are fully protective of safety in all conditions.
The only way this will ever be proven is through the simulations now being done at Boeing and RR (challenging!). If it is ever established without doubt, it will lead to the biggest shake up in Jet fuel testing in two decades.
Pinkman