I've wondered, not least because despite not even liking their page, Facebook continues to 'recommend' I attend their events, if they enforced a female-only policy and if doing so could open themselves to exposure under anti-discrimination laws.
I'm certainly not experienced in anti-discrimination law details, however my general understanding in SA is that it is allowable if the association (of people) also holds events exclusively for the other gender as well, which is something Snatch and Grab don't do, but it may be enough that the bars themselves do it and I believe there is 101 (not exact number) exemptions including 'gender promotion'. But that general view is SA not NSW where the events are held.
Anyway, if they do generally exclude males at the door, hopefully there has been advice sought on this.