TheShadow;
Wind that trimmable horizontal stabilizer into a fully nose-up deflection and its chord-wise airflows are very adversely affected. At 40 degs AoA those chordwise flows would be minimal and so the tailplane's efectiveness would be greatly compromised.
I don't believe the tailplane was as compromised as you posit.
AF447 - Thread No.6 will provide you with an alternative viewpoint.