I am talking about the time they have entered the game already and can see the realm list.
There it looks abandoned.
I wish I could read the family histories (it's still broke although being classified as resolved on the bugtracker) , then I could tell you when the last SoA player left...but I guess that's 3-4 months.
I think that is enough time to delete a realm...
I know there are worse things, but hey we should not forget the detail.