Just rejuvenating this thread and won't mention 'the other' event.
The double engine TCMA-directed shut down on the 787 in Osaka in 2019 was a result of the systems working 'perfectly' but in circumstances to which the TCMA was not intended to respond. Designers are aware of the almost infinite capacity of crews to inadvertently or even deliberately do ‘odd’ things with switches, knobs, levers and other controls, in combination and in quick succession, but it is almost impossible to consider the many combinations and analyse all the consequences.
Contrary to my earlier surmising that any sensor measuring ‘in the air’ versus ‘on the ground’ could drive both TCMAs on the 787 to the ‘on the ground’ state, a ‘whole of aircraft’ ‘decision’ is made that the aircraft in ‘in the air’ or ‘on the ground’, taking in consideration all of the sensors and, in the case of 'disagreement', disregarding whichever of them is most likely to be erroneous. The probabilities of the 'aircraft' 'choosing' the wrong state are, consequently, extraordinarily remote. However, it does inexorably lead to at least one input common to both TCMAs, does it not? That single point is the source of the 'in the air' or 'on the ground' 'truth'. That 'truth' was true in the Osaka event, and let's hope it always will be on every aircraft.