This ^ is the problem.
It's not the fault of the Australian courts, it's the fault of Australian legislators who made the law.
My (probably mistaken) understanding is that whereas the UK Equality Act has separate protected characteristics of sex and gender, the corresponding Australian legislation does not, and sex and gender are treated as the same thing. So if you identify as female in Australia, that's what the law says you are.
Happy to be corrected by people who know better than me
( After the FWS case I seem to recall watching a webinar from the LSE where I think Ben Cooper mentioned this and said we were fortunate in the UK that Parliament had had the foresight to distinguish between the two)