You're saying that Autopilot cannot be blamed for this failure, because you take it as an axiom that Autopilot doesn't cause this kind of failure? That's just an empty tautology.
Failures are failures, you can't just assume they don't happen on such a complex system.
Autopilot has not been observed to behave like this. That's not an "axiom", it's "evidence". I'm not saying it can't happen, I'm saying that the data we have suggests alternatives as more likely.
Failures are failures, you can't just assume they don't happen on such a complex system.