Jorah knew that a woman's rage was dangerous if gone unchecked, especially one with the power Daenerys had. He could see the fire in those violet eyes of hers and knew they were on a razors edge.

"The Frey's will not suspect an attack on them, the old man would be more than willing to wish to speak of peace. If you wish, you could send your Unsullied in to remove all those who are not related to the Frey's. Then, upon Drogon's back, unleash your fury upon their great castles with your children who were unjustly robbed of a sibling." He said. Unleashing her dragons upon a hated family would strike fear into all lords who would think to oppose her, but removing innocents would show a hint of mercy and show that she was not her father.