Just a thought, how about the airspace reverting to Class E instead of G when the tower closes (as it does in the US - even when there is no radar coverage in the terminal area)?
The critics of the NAS did not want procedural E at LT, the result was reverting to the previous airspace model and the installation of radar at LT. Now we have radar why can't the airspace be changed to E and have MC provide positive separation between IFR and traffic information on VFR?
In G there is no separation standard listed therefore there was no airprox. The ATSB will say this in the report, just as they did in both the previous LT and ML incidents (if my memory serves me correctly) where IFR/VFR aircraft converged in Class E (in the ML case observed on radar) and an RA occured (if my memory serves me correctly again - please correct me if I am wrong as i don't have time to re-read the reports).
As previously stated TCAS the last line of defence, this was made abundantly clear by the critics of Class E last time. Therefore it would be unwise to say that in Class G if you don't get an RA everything is okay.