Can the Royal Line legacy let a Citizen decide the successor, and how can that be stopped?

Question

Accepted Answer

Yes. A Citizen holding the Royal Line legacy decides who wins a Successor victory, whoever holds the Scepter. To stop it, exile that player, or let an Exile win so the legacy leaves the game.

Oath: Chronicles of Empire & Exile

Can the Royal Line legacy let a Citizen decide the successor, and how can that be stopped?