It's true, really.
Sat on Stealth today, waiting for launch, person next to me (adult)....
"What's that wire going to the top?"
Me: "That's so if the train gets stuck at the top , they pull that cable which pulls out a valve at the top causing the whole frame to deflate, lowering everybody safely to the ground!"
My co-rider looked up to the top and declared, "makes sense"!