Life In 19x19

Zen continues to beat up Japanese pros, but I noticed today wise old Yoda Norimoto scored a rare win by resign (and a loss by 3.5) with a cute little endgame reduction tesuji that Zen missed. Not sure who would have won if Zen avoided this: some moves ago Zen had cut at 2-3 at top left: if black answers this seems to achieve nothing, but if black ignores does it stop a 1st line attachment tesuji on top? Meanwhile Yoda played some gote moves to setup up the tesuji.