The problem I see with the LDS argument against pouring is that it can be applied to the LDS Church itself. As I’ve mentioned before, LDS practice a washing and anointing ordinance, called the Initiatory, in the temple. The form or mode of this ordinance has gone through changes, where it is not performed as it was, and is now a “symbolic” washing and anointing. In the same way that Catholics are accused of “changing the ordinance”, the LDS Church itself has done the same thing. So really, the argument from the LDS side cannot be the mere changing of how an ordinance is performed (since they have changed how various ordinances are performed, such as the Initiatory), but whether such changes were authorized, i.e., whether the Church doing the changing had such things revealed to them by God, and/or the binding/loosing power.