Soooo, he left a loaded Jennings unattended on the bench at a public firing range? Is this correct? Doesn't sound like a dumbass move to me at all.
My SOP at the range is to leave the action open, and the ejection port up, if for some reason I have to set the pistol on the bench. Just somethin' that was drilled into me by various instructors over the years : Don't chamber a round until you are ready to shoot.