Whoever wrote this has absolutely no grasp on how medieval society worked. Kings ran the country while queens controlled their castles. A queen that ran the daily operations of a country would be supported by a MASSIVE faction. Any normal lord wouldn't dare lay a hand on a queen that powerful. Secondly, threatening to kill a high ranking family thats still loyal even after you killed their family member sends a pretty bad message to your followers. Even with his magic win button ring he'd still just get assasinated while he slept.
The royal family doesn't die young because of the magic. Its because they're stupid...