The article said the barrel hit the floor and the gun discharged. Lots of older-style Colt pistols will do this. That's why Colt changed over to the Series 80 firing pin.
Not true.
I believe the series 70 guns had a rare potential for AD when dropped on the hammer, not the barrel.
Correct.
The firing pin lacks the mass to impart sufficient inertia for a discharge as the result of a drop. The issue was people carrying them at half cock under the mistaken belief that it was safer because pulling the trigger couldn't drop the hammer from that position. That tenet is just plain wrong; 1911s should be carried C&L or hammer down. A series 70 type 1911, if carried C&L or hammer down, is drop safe. The half cock position is a fail safe, intended to prevent the hammer from hitting the firing pin in the event that the sear is disengaged without the trigger being pulled. The firing pin itself is also an inertia design; it does not extend beyond the breech face when flush with the rear retainer. Ergo, it requires a hammer strike to have sufficient travel and energy to ignite a primer.
Do not carry a 1911 at half cock, and you will have no problems.
A Colt single action
revolver (or copy) is another story, though. If one is inclined to carry such a weapon, it needs to be carried either with an empty chamber under the hammer or with the firing pin resting between cartridges.
As for the incident, in the absence of sufficient information, the best we can deduce is that:
1) it was a cheap gun that actually isn't drop safe.
2) the gun was in a state of disrepair that rendered it not drop safe
3) most likely, trigger was pulled, be it a finger or hanging up on something else carelessly stored in the pack.