I spoke with ShopMate Customer Service this morning. They advised me that they require a license to on-send the coins to Australia. I asked for details regarding this 'license'. They were unable to provide any details. They suggested I speak to Customs. When I advise them that I already had and that there were no issues with importing collectible coins, they just 'shrugged. I rang Australia Post who advised me that ShopMate, while badged as an Australia Post enterprise, is really only a franchise. They knew nothing of a license stipulation either.
ShopMate will send me details of how I may be able to get around this dilemma.
Like a dog with a bone, I'm not letting this one go. I will escalate with management (if I can find out who that might be). Fortunately, this was an experiment and will only cost me $70
Incidently, I wrote to the Canadian Mint as to why they don't send to Australia, No response.