This sounds like one of those "can God make a rock so big He can't move it" types of arguments.
Mary was not created ex nihilo, as was Adam (and by extension Eve). She had both a human mother and father. Sin comes generationally through the father. Unless Mary's father were also born sinless, she could not be. And so on.
Since Jesus had no earthly father, original sin was not passed to Him. He was the only person born sinless. He was absolutely unique in that regard, being without original or actual sin.
Of Jesus (not Mary) it is said, "For He made Him who knew no sin to be sin for us, that we might become the righteousness of God in Him."
This is the same error Harley is promoting. We simply reject the premise: it's not in the Bible.