This seems like another one of the "choices" the TSA keeps telling us we have. They are going to try to make one member of the party go through the NoS to prevent the entire party getting groped. Also, this will probably be used by the TSA to say there is an increase in the number of people "voluntarily" choosing the NoS.
This does seem to be a potential security problem. A group could definitely take advantage of this by letting them pick their method of screening.