They're responsible. Holding the contest means they assumed an obligation to check out the risks. This is particularly true for contests where contestants are pitted against each other in endurance type situations (staying awake contests, etc.) IIRC, one station had a contest where contestants had to keep touching a new car, and the last person touching it won. They gave the people bathroom breaks every couple of hours, but also kept a doctor on site for the entire duration, since they were there for several days.
Yep - I've planned and supervised numerous promotional events over the years - although nothing like this, because I avoided such things at all costs - and we always had medical personnel and legal experts, everyone, give it all a thorough going-over before anything went public.
This contest was just a despicable and incompetent thing to do, all for the love of the "extremely extreme" these days. (No slur intended on our esteemed FReeper thread host, you understand.)