Phantom is not the King of the Infinite Realms.
While such a position does exist, Phantom doesn't hold that station. His position is much greater. He's the Realms' Protector, he serves the Realms herself. He has his own set of rules and laws he must follow, sorn by him to the Realms Herself, and those laws and rules are the only ones he must follow. He doesn't have to heed the King, nor the Ancients, or even the Observants, much to their dismay, Phantom follows the Realms and her alone. He will act to keep her laws, and the Realms safe, and hes one of the few that could dethrone the King should they prove themselves a tyrant or an otherwise poor ruler.
Its been nearly 200 Millennium since a Protector has been chosen, its such a rare title to be bestowed, that Phantom is respected very highly.
But, that is a source of its own problems.
There is many a denizen that think that, because Phantom was picked by the Realms herself, that he should be the King instead.
Those that support the King, however, see the need for a Potector as treasonous. The King won their rightful place, they should be respected, and the Phantom needing to be Protector, to have the right to strip that title, is blasphemous.
The only reason a civil war hasn't broken out is because Phantom's Faction knows Phantom can't act without good reason, and the King's Faction won't act without the King's order. Everything is at a tense, political standstill, and everyone is waiting for the other shoe to drop.