Since I've found out that kings will have all their decor removed and returned to hoard when retired, why not just let it stay there like the way lionesses do?

Or maybe we can still equip/decorate them as much as we like, because it's my king and I want to keep him pretty >3<

There should be a button that says ''Keep his decor'' when retiring him. If yes, the decor stays equipped when he goes to the dynasty, and can be removed at any time.

Let's say I want to put decor on a dead king. You'd go to their dynasty page and click a button that brings you to a page where the decor that you have in your hoard can be applicable.