You could argue that the point of going public is not to win against her accused, but to damage the liberal party as a form of compensation and to drive changes she feels need to take place at Parliament house.
I assume she is no longer employed, and therefore is not risking any potential career damage had she gone public while the incident was fresh.
I really struggle to see how she wins a rape case without evidence beyond her recollections of the incident, and the fact the report with the police was filed a couple weeks after going public tells me this is not the primary motive.
Rapes are very hard to win convictions on, so going public and damaging the person and/or organisation in the court of public opinion is an effective work around. Driving postitive changes is a good enough justification for some, and maybe they are right.