I can only speak from my own experience of flying in awful turbulence in a Cb.
All I did- after the autos jumped off- was to try and hang onto the attitude.
Couldnt read the ASI (!), but pulled some power off to slow down a bit.
Accepted the vertical speed the Cb gave us, (in our case it was downwards) and just concentrated on the attitude. Wings level, didn't trim, kept the AoA at usual value.
Hung on like crazy and waited for it to stop!
I was so maxxed out flying it was all I could do to put the 'belts' on.
I'll be amazed if these guys did anything else.
At least by having the AP and AT go off on 447, it left them with the power they had and the trim/ attitude they had. No bad thing really.
Their ASIs would no doubt have been 'all over the place' due to the big gusts/ turbulence etc but probably unreadable too. Maybe this is when the speed disagree messages were generated.
The a/c plainly then came apart either without any further input from them, which is quite plausible. Or maybe after some erroneous input from them which is also plausible and quite understandable-an attempt to maintain altitude, for example.
The big Boo-Boo was going in the Cb in the first place. Like I did.