Maybe I am missing the point here but the AOA's didn't fail. Why is that so difficult to understand.
The AOA's became fixed due to ice because water enter the sensor housing due to inappropriate ground equipment being used.
The AOA's presented their signal output to onboard systems after they froze at 32,000 until the end. You cannot pre-empt that scenario. You cannot detect that event you can only at best warn of discrepencies between the 3 signal sources.
But the dilema of selecting which of the three is faulty has been at the root of previous accidents. Not just involving air data sensors (Korean air 747 adi)