This sounds obsurd, but the guy needs to install video cameras pointed at all this computers.
If its truly educating his family that is his goal, the sheer obtrusiveness of this idea will prove a point and make family members careful. And if they truly are ignorant of possible threats and do something that compromises security, then they can go over the footage together.
Should be easy to install, fairly cheap and get the point across.
How did this make front page?