That transcript is so sad.
This was not AF447 so what on earth happened? I'm guessing inadequacy of some sort and that's on the industry as a whole.
If company culture doesn't strictly enforce callouts 100% of the time, it's easy to get into a routine of everything being just fine 100's of times until it isn't.
Really these sorts of things show there should be a failsafe mechanism that provides tactile/haptic feedback to the pilots if the other inputs are "fighting" theirs.
Even an audible alarm isn't enough, as you'll likely get more than a few of those during events where it matters.
Proper CRM of course should make this "impossible" - but in high stress moments any more layers of swiss cheese you can add the better.
I have no idea why the pilot-monitoring would have taken his controls. Or why the pilot-flying wouldn't have called him out for it. Possibly a seniority issue - we've seen similar issues before. Hopefully the french aviation authorities can determine the root cause.