I think that admonition relates to not storing guns in a loaded condition, and relates more to the hunting and target-shooting audience more than the CCW audience.
It covers all situations.
Always keep your finger off the trigger until ready to shoot
Always keep the gun unloaded until ready to use
If NRA training says that a CCW holder should be walking around with an unloaded gun, and only load it when in the middle of being attacked, then I would strongly dis-recommend NRA training for CCW holders.