I can't visualize the mechanisms and design for this ride. A free fall from that height would be ~72MPH, so the cables are controlling the seat speed at all times. The cable became disconnected on the way up. I do consider it a design flaw to have uneducated folks, that have no control over the situation, exposed to a loose cable in motion. That kind of thing is for folks who are working with, setting up, and controlling the mechanism and load. ...like a crane, or winch operator.
W/o seeing it, I'd guess the cable was installed improperly and ended up taking most of the load(load balance), or the end "splice" was bad. Neither of which might be readily apparent. could also be that the design allowed for a transient unbalanced condition between the cables. That would be apparent if there were wear marks on the seat guides corresponding to the seat cocking. At any rate, the cables should have been contained behind plates, or a strap placed to restrict cable motion in the event of one of the cables becoming loose, or broken.
That's a good point.