People buy those little derringers cause they are cheap. I helped run a gunshop arounde here for awhile, and the big sellers were Jennings and Loricin autos and those little Davis derringers.
The same guy who would come in and order a nice Beretta shotgun would buy a Jennings .22 to keep on the night table for protection.
I'd be interested to see if the weapon wa defective or if he was carrying it with the hammer cocked or just what. Not enough details to judge what really happened.
I have a friend, full time officer on the department I work for had a truly accidental discharge with a SW 39 many years ago. He was carrying it in a pancake type holster with a thumb break strap over the hammer and when he bent over to pick something up, it fired. Forunately the holster was worn in a way that kept his backside from getting nicked, but the bullet hit the ground about 6 inches from my foot
.
The bad thing is that very rare mechanical failure or not, the antis will use this to bash CCW.
Jeff