Here is the response by Fr Brucciani to the two SSPX Oblate Sisters leaving the SSPX. First things first; at least Fr Brucciani writes like a gentleman. Of course this should go without saying. However unfortunately in the past it has not always been the case when speaking of Religious leaving for the Resistance rather than, for example, the local Diocese.
As one would expect he also makes valid points, for example his use of ECCL. 4. Who could deny its truth? However, after reading it and mulling it over I wish to ask the following question. If this letter had been written in 1988 by Fr Bisig would he not have made the very same points? Why does obedience stop at the Superiors of the SSPX? Because of their past adherence to the fight for Tradition? One could make the same argument for supporting priests who left the SSPX for the FSSP or indeed the various Sedevacantist grouplets. Once they leave the fight for which people were supporting them in the first place, then laity do not 'owe' them obedience simply because they tell them to. Obedience is truly the one thing that the SSPX can not lecture on, for the existence of the SSPX is built on disobedience to legitimate authority gone wrong. Therefore the argument only works if one believes that the SSPX continues to believe what it has always believed, an argument which sounds pretty hollow these days.
I firmly believe that at the back of this style of thinking is an erroneous view of what the role of the SSPX is, and to tell the truth, it also exists within what is known as 'The Resistance'. It appears that both Religious and layman alike are under the impression that the role of the SSPX is somehow to 'save' the Church. What incredible arrogance, what pride! God could stop everything in one second. The role of both the SSPX and the Resistance should be to save souls. The way to save souls in these times of diabolical disorientation is to witness to the truth and let the cards fall where they may. This 'politicizing' of the SSPX has been a disaster. This is how we end up with them criticizing posters against Pope Francis in Rome or trooping to the local ecuмenical chapel for a photo shoot to upload on a priests retreat. Twenty years ago The Angelus magazine would have had an entire issue dedicated to exposing 'spin' instead we now have the 'non-polemical' wet pious platitudes worthy of of the worst Latin Mass Society efforts.
I think that the reason why SSPX laity have been so drawn to the letter by Sister Mary Elizabeth is that she wrote like the SSPX used to, like Bishop Williamson still does, and how the SSPX no longer do.