Hello. Yes, I am SSPX. I am still working, but I will be a pre-seminarian soon, and will be going to seminary shortly after that. I firmly support the SSPX and believe indeed that Econe will triumph in the end. But I also believe all traditional Catholics are on the same side, and we should be praying and working hard for the ultimate end goal of restoration in Rome, through a holy and traditional Pope.
In the Gospel, we see demons forced to confess that Jesus is the Son of God (cf. Mk 1:24, Luk 4:34). And this is well known in Church history also, for e.g. the demons were forced by the Mother of God to confess the power of the Rosary, before St. Dominic and several other witnesses. "Saint Dominic had hardly finished this prayer when he saw the Blessed Virgin near at hand, surrounded by a multitude of angels. She struck the possessed man with a golden rod that she held and said: "Answer my servant Dominic at once." (Remember, the people neither saw nor heard Our Lady, but only Saint Dominic.) "Then listen well you Christians; the Mother of Jesus Christ is all powerful and she can save her servants from falling into hell. She is the Sun which destroys the darkness of our wiles and subtlety. It is she who uncovers our hidden plots, breaks our snares and makes our temptations useless and ineffectual." http://www.how-to-pray-the-rosary-everyday.com/demontfort.html something they absolutely didn't want to do, and tried to resist for some time.
To the final objection, there are exorcists who say damned souls may sometimes be permitted to exercise influence over other souls. It is certainly a rare case, but not unheard of. Ven. Mary of Agreda says the punishment of Judas in hell exceeds the punishment of many demons. It may be as part of that that God may permit him to influence souls and then be punished by the exorcism removing him.