The power in Lid belongs to Demon Rood, as stated by Lispen
It was assume that power of kings goes to the next king, hence why Ruby stated that the power should goes to her. Of course, this decision was made without prior knowledge of Demon Rood being alive/Mia/hibernate
One thing to take note, Demon Rood disappearance and the power in Lid, are not a natural event. Something happen in the past that propel those event to take place.
I'm not surprised if Lispen turns out not to be a bad person with entirely bad intention in the end, it it really