It reads like broader organizational incompetence to me. From what I’ve seen:
1. They did safety analysis based on the original design: what needs to happen for MCAS to misfire (both the g-sensor and the AoA need to be incorrect) and what happens if it does (it runs once, to maximum authority of 0.6 degrees). They concluded from this that the issue was “major failure” rather than “hazardous” or “catastrophic”, and that the design met the reqs for “major” (2 sensors involved here, and major only requires 1).
2. Much later, with the analysis already rubber stamped by the FAA, they discover the low speed issue with stick forces and decide they can modify MCAS to resolve this as well, by radically increasing its authority over the stabilizers (more deflection needed to generate the same force at lower speeds) and removing the gsensor (which wouldn’t trip at low speeds). (This also seems to be where they introduced running it in a loop? Although some things we’ve seen out of Boeing seem to indicate that they might have not understood at any point that this was the way the system was written, or at least anyone involved in any analysis never knew to consider that)
3. Again later, someone concludes that the changes meet their initial analysis classification requirements, because they’ve already done a safety analysis and concluded “major”, which allows for 1 sensor with no redundancy, which they continue to have.
Nobody seems to have noticed that they’ve now fallen into a circular reasoning loop — the system must be safe to “major” level because we previously decided the system was safe to “major” level. They look at whether or not the changes still meet the requirements for “major” failure, but neglect to re-open the analysis and decide whether “major” is still the correct classification of failure in the first place.
Probably this means 1, 2, and 3 were being done by multiple groups of people with poor visibility and communication between them. Someone was asked to check whether the new setup met the requirements for the failure analysis the FAA had approved, but there was nobody looking at the bigger picture question of whether the validity of that analysis still applied.