Lowest BG for non-diabetics is typically between 2-4 AM. Your 70 was normal.
Technically you are correct she should bother to learn what the normal range is. But don’t forget they don’t need us we need them.
I would have refused the juice as well. I would have asked her to consult your endo because 77 is in your target range. There have been many occasions where I have felt that I knew more about diabetes than a nurse or non-diabetes doctor. But then again I live with it 24 hours a day.