@John Freas + some interesting images
With regard to the 777 autothrottle, this does actually physically move the levers. As I understand it the autothrottle provides an indirect control input via the throttle system through a motor drive to the throttle levers, and the throttle levers (and therefore any direct input to them) retain full command authority regardless of what the autothrottle is trying to do.
Also remember that most systems have 'off' buttons, and/or can be overridden via direct control input.
I know where you're coming from though,as what you described is the Airbus way of doing things, where the only autothrottle indicators are on the displays.
As for the AAIB update, I wonder what they're smoking to claim both the engines were maintaining power at above flight idle.
Look at the following images (guess you'll have to do it manually) to see what one engine looked like after it hit the ground while still at near idle speeds:
You might notice the way the blade tips have sheered as the lower part of the intake was pushed in, and the mud/grass on the blades. Though it doesn't look to have been doing many rpm at the time.
Now explain to me how anyone could see the other one as having been doing anything more than windmilling as it hit the ground:
The way all the blades are still attached and the right shape, and the lack of mud on the blades at the top sort of gives the game away, if it was still under any sort of power or even running down (as opposed to windmilling) there would have blades shed as the casing got crushed & mud picked up by the blades, as per the other engine.
The explanation of this incident should be interesting when it finally arrives.
(If you're interested, the above are part of a set of 24 images of the 777 on the ground, and give a better idea of the damage it sustained. There's quite a few holes in it!)