Mordekaiser is in the wrong Region

If you go to the Regions tab for the League universe, Mordekaiser is not found in Noxus. Instead he is found in Shadow Isles. Though, when you go to the Shadow Isle champs (https://universe.leagueoflegends.com/en_US/region/shadow-isles/) it shows his region is Noxus. Rito nani?