OK, you switch ( or it switch by himself )from auto to manual due to turbulences. Why not ?
But :
1/ Why you have the nose full down until the impact ?
2/ Why the second Tiger of the team don't have the same turbulences and switch change mode ?
Many years ago, some same accident involve the "Alouette" family. At this time it was the horizontal stabilizer inflight broke . At cruise speed : 80 kts, the stabilizer broke and the Alouette fall down nose down....
Now imagine the Tiger at cruise speed : 135 kts the same things happen . ....