I disagree as I don't believe planning permission is ever granted for access to private property from a listed building. Even a balcony would be overhanging the party wall and not be acceptable. It might be different if it was to communal land
I'm not sure but I know historic England say that conservatories, extensions etc can be added to listed buildings occassionally. Listed isn't it can never change, it doesn't freeze a building in time.
However it's not relevant, I doubt this guy has permission, so he's in deep, deep trouble if he's just willfulky destroyed part of a listed building.