That is in essence what I am saying.
The simplest case is a private airfield with no ATC and no published approaches. There is no rule to restrict a GPS-based home-made instrument approach down to such a field. Minima apply to published approaches.
Note, that I am not attempting to cloud the issue with the specific privileges of the IMC rating, where as we know, landing or taking off in less than 1800m is not permitted.
By focusing on the simplest case of a private field, I am also removing some of the other confusing practical issues, such as the Management of an Airfield denying authority for an aircraft to land below certain weather minima.
If the argument is focused on this simplest case, I think you'll find that there is nothing in legislation to prevent such an approach. This is not to suggest that it is sensible or safe.
2D