GP Elevation
In response to previous comments in this thread regarding GP elevation, the ICAO recommendation for a standard ILS is that the GP elevation should not exceed 3.5° for CAT 1 ILS ops.
However, where States have a need to implement GPs exceeding the recommended 3.5° elevation angle (non-standard ILS), ICAO recommends that the approach charts be annotated accordingly and the relevant regulator restrict use of the ILS facility to approved operators and aircraft.
If a non-standards ILS was installed at OOL, it's use would be restricted to only a few operators who have the necessary CASA approval. That fact alone probably undermines the cost/benefit argument for an ILS.