So much for your “strawman” argument......
IMO, the Airbus “Flight Management System” is suspect in AF 447. Its “screwed the pooch” very dramatically in the past. All too easy to place blame on a dead flight crew - as you imply - when no other evidence is apparent; or needs concealment. Happens all the time...... >PS
My guess would be that a number of factors were at play in this case. Programmers and aircraft engineers cannot foresee every possibility in such a complex system. When such a system is put into a very challenging situation and equipment starts malfunctioning... it is no real surprise that the end result could be a crash regardless of the actions of the flight crew.
I know my own experiences are only anecdotal here... but my wife and I once had to divert all the way to Utah to get around a weather system on our way to her sister's place near San Francisco. Along the way we were dodging thunderstorms and fighting with some pretty severe turbulence. Thirty miles out from Bend Oregon we heard a commuter plane say that they couldn't land there because it was a level 3 thunderstorm and it was way beyond their capability.
We ended up landing to get fuel at a little place called Christmas Valley in Eastern Oregon. The twin engine plane that landed ahead of us had been hit by lightning and it had destroyed virtually all of the electronics in his panel. They were shaken up but not hurt. Supposedly when a plane gets hit by lightning it passes around the skin and doesn't go through, but I have seen planes with holes from lightning.
I know the electronics on these fly by wire transports have redundancy and are protected from lightning. But those of us not thoroughly familiar with such things can't help but wonder if the effect of “1.21 gigawatts” ; ) on a computer system can really be adequately planned for. Can the electromagnetic energy from a large bolt of lightning cause some fluke glitches in even a well shielded computer system. Despite assurances to the contrary I still wonder.