Their lore places any of them no where near Ionia. Even in their stories for things like shadow and fortune the nearest their settings could place them is Bilgewater. Riot coulda given Varus or Irelia a blood moon skin (god knows they haven't made a skin for either in forever) but instead of riot keeping to themes they went for some badass looking ones. for the longest time in fact there were more champs with the blood moon skin theme that weren't involved with ionia then those that were.
blood moon akali (2011)
blood moon shen (2011)
blood moon kalista (2014)
blood moon elise (2015)
blood moon thresh (2015)
blood moon zilian (2015)
blood moon yasuo (2016)
blood moon kennen (2016)
I guess what Im saying is no one knows better then riot the theme for blood moon and they dont care if the champ they use the theme for has any ties to ionia and i dont think it matters anyway. All the blood moon skins did was help depict how the champs could look in ionian culture.