You have to consider the well being of the marshalls and also take into consideration the fact that if you have numerous cases of hypothermia already, then decide to continue, you run the risk of being overwhelmed by freezing competitors with little chance of getting them all to safety fast enough. Not to mention the fact that if someone dies, you as the organiser will face the question "why did you continue the event given the circumstances" and the very real possibility of being held responsible for that persons death. They made the call and I suspect it was the right call.