It was already noted that both the riders involved in the incident were employees. Don't assume that the restraints were carelessly left unchecked. This may be yet another example of the shenanigans that probably go on at parks where people who have the means to do so will take unreasonable risks just because they can.
I think most of us know that one of the English phrases most likely to result in someone visiting an emergency room is, "Hey, guys, watch this!". Add "Hold my beer a minute" and you have a recipe for disaster.
I think there is a non-zero probability that this was not the first time these particular riders had ridden the ride without the "safety gadgets" in place.
--Dave Althoff, Jr.
"The minute these things don't scare you, that's when you're in trouble." --J.W.