My wife and I were discussing this story this very morning after she saw it on the news and the very well put point that romilayu makes here is the ultimate conclusion! Stupid is stupid no matter what you teach them and you can't teach people to use their head if they are stupid!According to the information you cited in your original post, I would have to say "Probably not." The incident you posted above was exactly what you are prescribing. The man, a "trained" CCW holder in the state of FLA was showing his friend his gun, one could argue even, "teaching" him - and yet, the poor girl still got shot.
What you and what every other trainer will never admit to is that there is no level of training that can accommodate for lack of intelligence. And while some may dismiss this arguement because Ron White has a stand up show of the same name, it doesn't make it any less true. You can't fix stupid. No amount of training can penetrate the mentally inept. Even after hours, days, and months of drilling....all you will have is well trained moron.
They exist everywhere...and the reason no amount of training will matter to the moron? They lack the ability to link the training to life. "Training" takes place "in class" and "class" only happens at "school" and "when the bell rings," they aren't at "school" any more and so they cease to utilize their "training." At the risk of being glib...you can lead a horse to water, but you can't make him drink. You can give the moron all the training in the world...but he still has to use it...and he won't...why? Because he's a moron.
Not because he's untrained.