There is no law in the US prohibiting me from creating an alternate login screen for one particular customer just in order to capture their login password. So as a US citizen I have no defense within Australian law against an Australian demand that I capture the password of one of my users... perhaps a parliament member of the Australian opposition.
I can choose to simply ignore the demand. The US will not extradite me for violating a foreign law that does not have an equivalent in US law. But I suppose I can never go on vacation to Australia.
> Circumventing an electronic protection
> Unauthorised access
The company providing the protection cannot by definition circumvent it or be unauthorized. If a third party decides to deliver a payload to your browser to discover your Facebook password, then they are violating the DMCS in the US. But if Facebook decides to deliver a payload to your browser to discover your Facebook password that is simply them doing business in a different fashion. This isn't a violation of US law, so refusing it do it would be a violation of Australia's very poorly-considered new law.
Now if the TAN/TCN was issued to a US based company that would be a different issue but then you as an individual would not be in violation of it.
Not that that makes it a better law, but I think for people not physically in Australia the risk of being issued an enforceable (under Australian law) TAN/TCN is quite low.