Brett would be correct. That was my exact interpretation - and I've always seen it enforced like that.
The CT ward was DIRECTLY in the hostage rescue zone, not close by... There were no hostages being rescued at that time, but it was definitely IN the area. So just to be clear on the exact rule:
You may ward the hostage zone as long as it does not DIRECTLY interfere with hostage rescue and leaves a path to somehow get there. Would that be correct?