It was probably already half dead. With the pressure difference between the surface where it was caught and where it lives, its body was going crazy with the lack of pressure. Deep sea creatures who live at depth depend on the pressure and if it is gone, then its body can't function. Like the article said, it was probably sick so it had floated up to the surface to die.
Still sad, but would of suprised me more if it didnt die within a few hours