Why?? Christ is the continuation and fulfillment of God's promise to KING David that "his line would reign forever". Mary is the Mother of Christ. In eastern kingdoms (including Judea), the reigning queen was NOT the King's wife, but the King's MOTHER. So, yes, Mary "is" Queen. So Hahn is correct, both historically and biblically.
And Hahn covers all this in his book, which, since you appear not to know the above, I assume you have not actually read, but are criticizing anyway.
I disagree that Mary deserves, or should be assigned, the title of “Queen”.
But that is because I believe you put too much emphasis on Mary as the Mother of the King.
Jesus as Man was not King. It was Jesus as God that is King (I bet I’m going to get into trouble for making that distinction, and I’m not trying to make too much emphasis on it).
Jesus said “my Kingdom is not of this world”.
Mary was chosen by God to be the Mother of Jesus, but there is no indication he was chosen to be the Queen of anything.