"The point is actually quite clear, if a moderator is overruled then the moderator is owed an explanation and an option to see the reason for un-banning someone."
I don't think this is enough. Insubordination should not be tolerated in a chain of command. If someone goes to the boss and says he has been banned and he thinks this is unfair, the boss should tell the person to go and explain why he thinks he should be unbanned to the moderator who banned him. If DS had been willing to have a civil conversation with me and explained why he thought he should be unbanned, and been willing to listen to why I banned him, I would have been happy to give him a second chance myself. I was perfectly capable of unbanning him. If you overrule the decisions of those who've been delegated authority, without giving them an opportunity to resolve the situations themselves, it encourages insubordination.