Southwest should sell seat-saving cards for $25 each. Buy as many as you want and save as many seats as you want. The cards are good only for that flight. If the seats are needed for people, oh well too bad. But you could save an adjacent seat up front with your A10 boarding pass for your traveling companion in the C group if it's worth it to you. I suspect most will pass on the "offer", and at that point Southwest can make an official policy of NO seat saving (without buying the seat-saving card).

Just like if they charged for pre-boarding (which they can't by law), obviously the number of pre-boarders would drop like a stone. Charge for seat saving and the problem disappears and WN makes a few bucks from some people. win-win