If the Captain and or F/O were used to flying outside of Australia they may well be used to doing visual approaches at night.
Neither ICAO, EU-OPS or FARs for example prohibit visual descent below MSA at night, and most companies allow this with certain provisos:
E.g.
The line of sight is also the line of flight.
A lit area (usually) the runway is continuously in view.
etc etc.
If this was home base he probably knew the terrain beneath him
It could be he breached a national regulation and or a company rule/SOP but, whether or not it is unsafe is a totally different argument.