The BQ has his memories so she could easily know that phrase. If the BQ is Jurati, she may be using the memory to get through what she knows is Picard's fear of the Borg. A fear which touches on the primal fears he had as a child. My guess is they may figure out whatever puzzle Q set them, get back to the future with Picard knowing this is Jurati/Queen and then cancels the auto-destruct.I don't think so. If you notice, the Borg Queen's voice changed to a more female voice when she says, "Picard, look up", which suggests to me maybe he was lost in thought about his mother and mistook what the Borg Queen said. I dunno. He didn't look up though.
Or maybe, Isa gets a knew role as BQ by the end of this.