have evidence the pilot did not maintain VMC?
Well it would not be the first time, late last year I was planned YCAB-YBSU-YHBA when ATC gave me direct YHBA not long after leaving YCAB. Levelled out and then they give me traffic of a VFR aircraft, lets say a piper twin that was very close by and descending through my level.
Now if I had been in VMC at the time my heart rate would have raised a fraction only as I tried to make visual conatct. The person in the RHS that day was from BNE CEN and he was gobsmacked, all we could assume was this guy was bombing through a small hole in the cloud, but I can be pretty sure there were none anywhere near us by the darkness and what we saw as we entered cloud from underneath. The base was 3500-4000 so we had a good look on the way out of YCAB.
I mention no names or places where the aircraft was from to protect the guilty
but I am sure this goes on from time to time and its not really funny in a busy area like SEQ. So it could well happen at Barwun Heads also.