Traditional Catholic Theology teaches both that Mary was sinless and that Mary needs a Saviour.
Anyone who is taught only one of the two points is receiving defective instruction.
And if Mary was born sinless then her mother had to be as well and her mother and her mother ad infinitum.
So it contradicts itseslf.
Mary was FULL of Grace, and that enabled her to live a sinless life. If a blind man falls into a pit that he could not see, one could save him after the fact with a rope or ladder; but he could have been saved before the fact by being told of the pit in front of him. That is what the total INFUSION OF GRACE did for Mary; the Angel of the Annunciation even addressed her thus.
Read his passages for yourself and tell me where the heck he derives his premise.