Yes, tween nodes continue because they are coroutines.
The reason why the Rotation is done first, is because you updating the rotation in the graph Update, while the Shake is done with a coroutine and as usual, normal Updates (eg graph updating) is done first and before Unity Coroutines update (coroutines are always updated last).
Is it possible for you to use Tween Rotation directly, instead of using Tween Quaterion + Set Rotation in update?
If you use Tween Rotation and Tween Shake (thus both run as coroutines) then the execution order will depend only on which node of the two was executed first. The first node to execute will also update first (since its coroutine is registered first).
Gavalakis
