Grandmothers occasionally demonstrate unique power to call people back to their humanity. Whether or not you agree with all that is said by this particular woman, you can sense the power her words have for the young man she is speaking with.
This reminds me of the story of the group of mothers and grandmothers in Liberia, who protested the civil war that was taking place there--at one point taking their clothes off and positioning themselves so the militants and generals would have to step over their naked bodies. This created so much shame for these "leaders" that they reconsidered and turned from their violence. An extremely powerful story. The movie about this is well worth seeing (and can be read about here: http://praythedevilbacktohell.com/synopsis.php).