More On The Mordechai

As I noted in the comments to my last post what is really bothering me about the Mordechai is that by the blind person, there are two people involved and Reuvain the blind person is being motzei Shimon. When Shimon fullfills his chiyuv he fullfills his chiyuv on a d'oreisa level even though Reuvain's chiyuv is only d'rabanan. By the kiddush before tzais case Reuvain is in effect being motzi himself. At the time he makes kiddush he is only fullfilling his chiyuv d'rabanan. His potential chiyuv d'oreisa will never be fullfilled

The Ksav Sofer (Shut Ksav Sofer Orach Chaim 99) has a lengthy teshuva on the status of a koton who becomes Bar Mitzvah in the middle of sefirah. At the end of the teshuva he quotes this Mordechai and he basically says that what was bothering me is in fact the chiddush of the Mordechai. I guess the Ksav Sofer wasn't bothered by this chiddush because he accepts it at face value. He also seems to write the same idea as R' Elchanan (see here from R' Chaim ) although he manages to write it in a few words.

As an aside, this teshuva is filled with different sevaros from different sugyos in Shas on the whole inyan someone who was patur and now becomes chayuv (This would apply to a koton, a ger an eved and someone who was crazy and now is sane). It is definately k'dai to go through if you are learning this sugyah.