"However, if it is KNOWN that there will be an emergency landing,"
Most emergencies to date have been UNplanned.
CASA does, however, recognise that a passenger seated in an emergency exit row may be called upon to assist crew members - this means not only opening the emergency exit, but also assisting with other duties, such as I have outlined above, eg. restrain pax from overcrowding the exit in use, or be used to stop pax from evacuating through an unusable exit.
CASA are placing the responsibility on the airline.
The airline is placing the responsibilty on the F/A's.
The F/A's are then advising exit row pax that THEY may be responsible in an emergency situation. This applies especially to overwing exit pax, as F/A's are seated ONLY fore and aft, and are unlikely to be able to get through the melee of pax, following an accident!