It comes down to paperwork and rules and regulations. There is nothing about risk. the boffins in the office will talk risk and flight profile blah blah blah.
Australia doesn't have "Public Use" aircraft, like they have in the USA. So therefore anything that is flown is either Military, do what you want according to your own "military rules", and there is civilian. Civilian Aircraft must comply with civilian ie CASA rules.
CASA say that to use an aircraft it must be Type Certified, so now the Blackhawk is just a big Huey. you get them from the military, get a "Restricted" TC, and generally it is "restricted" to certain Types of Operations, being Fire fighting, Lifting, Ag Ops, and a couple of other things, but definitely NOT Carrying Passengers.
The difference in the USA is that they have Public Use aircraft, which I believe they are able to carry passengers in Carrying out Public Duties, ie Fire Fighting, Police, some SAR/Ambulance, under certain conditions, ie you cannot set up an airline and fly city to city, but you can carry pax for specific tasks. Not so in other countries!!
In Australia the Police have to play by the Civilian Rules, the Fire Fighters have to play by the Civilian rules. If you want to carry pax you need to get a Civilian Aircraft that is certified to Standard Category, get an operator with an Operating Certificate that allows passenger transport, and you are all good, or the Police/fire, whatever can get their own operating certificate. So far CASA have control over the RFS Aircraft, and RFS want to be able to operate like the fire service in the USA does. It is the same in a lot of other countries.
If they can get the rules changed for the Blackhawks, then you should be able to carry Pax in Hueys, OH-6s, Kiowas, suddenly every Restricted aircraft should be able to carry pax....
And please don't try to tell me that civilian aircraft are built safer and to a higher standard than the military ones. Has anyone ever tried to tell the US military or the any other Military that we have these perfectly good helicopters over here built to a higher spec than you require, but we will sell you the crap ones that no one else wants... Oh and they are no good for carrying pax, ah sorry what were the Huey then the Black hawk designed to do??