You never see it coming

it amazes me that when something traumatic happens quickly that even though you know what to do you can freeze. for example I went to visit my painter as he was working on my 340 swinger this week to check on the progress and take him some parts. as he was finishing up on some body welding he decided to take a break and chat with me. as he reached down and unplugged his welder he was in a half bent-over position looking right at me saying pull it apart pull it apart it took me a second to realize he was being electrocuted. I knew not to touch him and knew I had to unplug it at the source. At first I thought he was just screwing with me,, he managed to break free but it really shook him up up.
As a learning experience, what was he doing wrong?