The ruling from the Magistrates was emphatically not intended to mean that Mt Black Nastrond must remain free of militia. It was only intended to see that the militia that were brought over with the region due to the exploitation of the bug were disbanded.
Since disbanding militia costs gold and hours for the Lord, I don't think it's unreasonable that they be allowed to stretch the disbanding of it all over the course of a few turns. (Especially if there were more than 12 units to begin with!)
