The question is, why did the girt bar let loose? Was it not latched securely, or when the door opened, did the latch break? When the stewards close the doors, they slam the girt bar into place. Then in an emergency, the door is thrown open, the girt bar causes the slide to deploy. I don't know how but it does, I am not a steward. The bars were all inspected, properly latched, yet one let go after the evac was complete.
Parts break, or malfunction for some reason. It is nobodies fault, it happens.
So they tell me, I don't know.
But the evac has to be done again. It reminds me of my chaise lounge. One day the hinge just broke. I don't know why, I am not an engineer. But I had to buy a new one.