It's "fair enough" from the point of view of the airlines. The logic you describe works fine for them.
However, things look very dodgy indeed here as far as Boeing is concerned. They would appear to very been selling a safety critical indicator as though it was not, in fact, safety critical at all. This is on top of installing two physical indicators and only using one of them on any given flight and missing the entire MCAS out of the manual. It seems to me that Boeing may ultimately end up with a bill for the whole liability for the Ethiopian crash and the whole liability for the cost of the grounding of around 380 new planes and the whole liability for the delivery delays on new planes that should have be coming into service at the rate of fifty a month.