Some people do not assume that the engine controls reduce fuel delivery below idle regardless of the system and whether it's electronic or mechanical. Particularly in the diesel crowd, coasting in neutral seems to popular because they have comparatively limited engine braking compared to a gasser without a compression brake, retarder, or exhaust brake.
I would like to assume you skimmed over this part, but you clearly included it after trimming the rest of the post out.
Life is not a Michael Bay movie. The truck will not suddenly careen out of control, flip over, and burst into flames. The engine will continue spinning and you will still have power assist for the steering and brakes. Any competent motorist should be able to recover from a loss of engine power, particularly one that was initiated on purpose.
This is not a safe test on a public highway by any stretch of the imagination. Imagine someone trying this and oops... since I shut off the ignition I am having a really hard time making this turn when my steering locks and I kill someone else or crash into a tree and since I am now in a panic I don't think to turn the key back on.
The last thing I want is to have someone who thinks chocolate milk comes from brown cows to be trying this little maneuver careering toward me.