I think we're victims of bad reporting and/or lack of aerodynamic understanding and/or ignorance of just what the flight profile is normally like.
Exactly. And I don't believe for a second that the switch selection the may have lead to the feathering of the tailplane was done by mistake. A little way up someone posted the credentials of the crew. They were highly qualified and had over half a year of preparation for this flight. These pilots would not arm (or activate) a system at Mach 1 that must not be armed before Mach 1.4
unless they had a reason for it. Engine problems, control problems, whatever. But "by mistake"? Certainly not.