Guns that are safe when dropped have been on the market since 1911 , or earlier.
Old cowboy revolvers that we now call "single action" were so prone to fire when dropped that most cowboys loaded five rounds in their six shooter, the hammer setting over an empty chamber was their safety.
The double action revolver does not require that the hammer be cocked to fire , pulling the trigger will cock the hammer and also work the shear, thus "double action" a double action revolver does not fire when dropped because the firing pin is not engaged until the hammer is cocked.
Semi- auto pistols are generally like double action revolvers in this respect, plus a lot of them have "grip safety" so they will not go off when not properly held.
If this guy had a single action pistol , it was his responsibility to understand the special precautions required , if he had something special , or something so worn out that its safety features weren't working , the same, it is his responsibility to know his machine.
I still want to know the details of what the firearm was and why it fired when dropped, I might be responsible for the safety of such a thing someday and I would appreciate knowing what has failed before.
It could be something I would buy without knowing better,