I think brant is on our side with this one. He was responding to someone who actually doubted that Mary is sinless. What brant said is correct: Mary IS sinless, but she could not be without the anticipatory merit of Christ on the cross. Even if, somehow, Mary never committed actual sins independent of the anticipatory graces of Calvary, she was still directly preserved from original sin by God because of what her role would be in Christ's mission on earth, which was to embrace the cross that we might attain eternal life. Antecedent to the cross, but because of it, Mary was preserved from all sin. That's what brant was saying (feel free to correct me if I'm wrong brant!).
So you are saying that Brant said: "Mary IS sinless, but she could not be without the anticipatory merit of Christ on the cross. Even if, somehow, Mary never committed actual sins independent of the anticipatory graces of Calvary, she was still directly preserved from original sin by God because of what her role would be in Christ's mission on earth, which was to embrace the cross that we might attain eternal life."
then you lost me with "anticipatory merit"
Mary anticipated nothing. She was consecrated to God from age 3. The appearance of the Angel Gabriel took her quite by surprise, so much so that in her response she commented that she had never known a man. She was a virgin!
Bottom line: common sense tells us that God would be born of a pure vessel. There was no "backup" plan here. He prepared Mary for this role but asked her permission first. She accepted: "Let it be done unto me according to thine Word".
Imagine the reaction from those around her! What's not to love about this beautiful woman, our Mother!