Seem to have missed something here
Who is M.A. and what did he say?
1.3 is quite right. It is no longer really relevant what happened. The point is that no-one will ever know, and on that basis the finding of negligence is unsafe.
Their airships' dogged refusal to see that they have failed to reach the extremely high (for just this reason) standard of proof shows, in the words of the PAC, unwarrantable arrogance.
Simple really innit?