The land owners claim that this road is permanently closed for renaturation, that nobody, not even the land owners, may use this road, that the buildings at the north end of the road may only be reached from the water and have no vehicular access by land. If that is indeed correct, then (and only then) it could be possible to change the tagging to "abandoned:highway=track". Do we have any local mappers who can verify the situation on the ground? If what the land owners claim is true, we would expect some form of permanent barrier at the south end of the road, rather than just a sign or a lift gate, or at least signage that makes it clear that nobody is supposed to use this path (rather than just "private path").