I know. Leaving aside Louis' very much alive and scheming younger legitimate brother Gaston and three illegitimate brothers, plus a lot of Valois leftovers and other French nobility, all of whom would have been in line, AND leaving side that Armand du Plessis had no Royal blood connection at all and on his mother's side was even sort of bourgois, you'd think even a Hollywood scriptwriter would be aware a Cardinal of any sort can't become king. But that script apparantly really thought it was a cartoon where all ministers/vizirs want to become king. Head. Desk.