This bit is very relevant:
(iii) Permanent exemption—competitive sporting activity
The Act contains a permanent exemption in relation to ‘competitive sporting activity’.44 This is commonly referred to as the ‘single-sex competition’ exemption, although it does not operate to make all single-sex or single-gender sporting competitions lawful.
The exemption allows for discrimination on the grounds of sex or gender identity only in ‘any competitive sporting activity in which the strength, stamina or physique of competitors is relevant’.45
The words ‘strength’, ‘stamina’ and ‘physique’, and the term ‘competitive sporting activity’, are not defined in the Act. Their meanings have not been conclusively settled by the Federal Court of Australia.
However, in considering an equivalent exemption in the Victorian legislation, the Victorian Civil and Administrative Tribunal has stated that the exemption will operate if, when both sexes competed against each other, the competition would be uneven because of the disparity between the relative strength, stamina and physique of male and female competitors.46 This interpretation was approved by the Federal Court of Australia47 and the reasoning is likely to extend to people of different gender identities.
The objective of the exemption is to restrict competitive sporting activity to people who can ‘effectively compete’48 with each other. This is intended to recognise that ‘biological differences between men and women are relevant to competitive sporting activities’.49 It can be understood as ensuring a ‘level playing field’.
If a sporting organisation decides to rely on the ‘competitive sporting activity’ exemption to exclude a person from a particular competition, it will need to satisfy itself that ‘strength’, ‘stamina’ or ‘physique’ are relevant and how the organisation assesses this. Given the diversity of sports and the role of different skills and physical characteristics (strength, stamina, physique) in each sport, the assessment should be specific to the sport in question.
So it’s possible for women’s sport to protect their competition permanently.
“It will need to satisfy itself” of the bloody obvious. That won’t take long, will it?