The PF was trying to steer the aircraft forgetting that the autopilot was still engaged. I wonder whether this could of happened here...
Hmm, I've had that happen but it will try to put you back on the LOC, not the grass (unless you've already vacated and let go of the tiller...).
The photos *are* rather surreal: 200T+ of aircraft sitting on the grass like it was helicoptered in there... Normally, you'd expect the wheels to have disappeared into the ground and see dirty great ploughed tracks leading off the runway. Doesn't seem to be anything like that here; maybe German spec. verges are stronger than they look?