You're talking about a company that shipped MCAS in its new planes without training pilots on what it was or how it worked, resulting in the deaths of hundreds of people.
So, an argument that this murder wouldn't be rational, gives me zero confidence that it didn't happen.
Pilots were trained in how to deal with runaway stab trim. There were three MCAS incidents. The first one you never hear about because the crew followed the runaway trim procedure and safely completed the flight. The second one did not and they crashed. The third received an Emergency Airworthiness Directive that reiterated the procedure, apparently forgot about it, and crashed.
Yes, the MCAS design was defective. The crews didn't follow their training, either.
So, an argument that this murder wouldn't be rational, gives me zero confidence that it didn't happen.