I'm still not convinced, if the neck supports on the side of the cockpit can support such extreme forces in a sideways impact with a barrier (don't be deluded, in a high speed sideways accident the drivers head has no problem reaching the side of the cockpit, or even the steering wheel) the there is no reason to suppose they couldn't support the same forces acting from another car hitting the helmet.
It was mostly DCs fault, the youtube vid doesn't show it clearly but on TV it was obviouse he was sideways a split second before he hit Wurz, and therefore going too fast. David's front left climber the back of Alex's front right as Ciro explained and obliterated the Scott's suspension in the process, although didn't do too much damage to Wurz'. Alex could have seen it coming sooner, esspecially as he made a mistake on turn 2, alledgedly, so he should have been prepared for someone to take advantage at the next corner. But David took the blame and fair enough, he caused the accident, Wurz just didn't prevent it.