on the one hand it surely sounds crazy that three people were not able to realize a stalled situation and recover from this high altitude. we could think that everybody of us would have done better.
on the other hand, like TTex600 described very good, its a different story to discuss it aftermath or being in such a situation for real.
they went through the night, thunderstorms in the vicinity , systems shut down one after another. the copilots confused and start to loose orientation. the captain needs time back to the cockpit but cannot help much.
the pilots had no visual reference what pitch they have, the stall warning wents off when you pull further and goes on when you push so vice versa you normally would expect... ( because at very low IAS it seems to inhibit) . the captain seemed to be the only who had a feel for a possible stall, he advised several times not to pull- until the gpws went on and they tried the last instinctive pull without any result in a stalled condition of course.
i think you can blame airbus that the stallwarning is not designed to inform a pilot firmy about a stall in any event, even with frozen probes and false speed indications. the second thing of course to blame airbus is that the instruments at all went erratic.
the crew of course lacked to realize the true problem and , when not manouvering so that they will not reach a stalled situation, to recover the stall. from that high altitude the stall from a technical point of view should be recoverable.