Itche- I think that psak is actually found in bais haleivi 1:42 and quoted in eyn hatechailes. My shayala is is bal tigra like bal tosef that it only applies if you have kavana to be mosef on the mitzva ( ie therefore there is no problem with RT tefiin or succa shmini atzeres) or even if you are oiver with out the kavana to be mevatel like any other mitzvah?
