I think that those who advocate relying on ILS and VOR non-FM immune systems in class G are saying the aviation equivalent of "driving a car with defective brakes is OK if it has an MOT.
Well the CAA obviously think it is OK so far as the VOR is concerned. I guess they could have just as easily required FM immunity in class G for the VOR as they did for the G/S. The fact remains they did not. I wonder why?