The only reason I wouldn’t want to do that would be if Yvain is going to publish the pass phrases along with the data, for the curious. Then it would be publicly obvious which were my responses (not that I said anything I particularly care about keeping private on there, I suppose...).
Um, I might be being stupid but I think you can just announce your pair of words now in order to “lay claim to them”.
The only reason I wouldn’t want to do that would be if Yvain is going to publish the pass phrases along with the data, for the curious. Then it would be publicly obvious which were my responses (not that I said anything I particularly care about keeping private on there, I suppose...).