So, I think your opinion reduces to letting W/O's being counted as a win. The problem with that was discussed recently(can't remember where). The points brought up against that did convince me. What if someone gives a walkover before the first ball is played? Then participants can pick that player for a sure advancement to the next day. Situations like this tournament are extremely rare. Adding a provision for this won't make any difference.
We talked about time management some might get info faster or ealier then others, in this case if you changed your pick and i didnt its on me.
This time was a double WO it will happen again probably not soon.
In another scenario you pick has 1st serve. The other player falls and breaks a leg, he cant play, your guy moves on but you loose your pick. Your Back up pick Advances to next round due walover also and your tournament is done. And both your picks are still valid for thoer guys in the next round.