Nobody talking about that 'shock'. Though, to be fair, it was more dramatic in the anime. We also won't get the significance until the postmortem for this game, but Rei's basically already lost because of that move, and he's just fighting as optimally as possible, now, to delay the inevitable.
Reminder that I still don't really get the actual Shogi moves, but the way these scenes are written and presented can really give you a sense of how important certain moments are, even if you are lost as to what a given piece being where means.