There has been alot of talk on the server about the wards.

for one, Zero did state that Warding cannot be used to block objectives, for example a bombsite on the map or the hostage area/rescue zone.

Now it gets tricky here with the hostages being moved, technically you are doing an objective and the enemy is trying to kill you, I see it as a challenge and furthur play to rescue them so as long as your not placing them on the hosties, everything else should be allowed.