Chief Justice Chris Kourakis sent the matter back to the Adelaide Magistrates Court for further consideration, meaning an automatic suppression on his widely known identity was reinstated.
Mr Rau says there is legislation in the pipeline which would allow suppressions on alleged offender's names to be repealed to prevent similar situations.
"This is certainly a bizarre twist and that's why the law was amended by the Parliament last year, we put a legislation in to amend it," he said.
"What will happen when that transition has occurred, which I expect and hope will be within a very short space of time, is that the default position will be there is no naming of the person.
"But anybody, including the media, can go in and say can you please name them, because for example in the situation [we're] talking about now, this is absurd."
Mr Rau says the current laws were not designed to shield alleged perpetrators, and the legislation amendments will be gazetted soon.
"The law is there to protect victims, not to protect accused people because in many of these sexual offence cases, if you identify the offender, you may tend to identify the victim," he said.
Under the Evidence Act, mandatory suppressions apply to a person accused of a sexual offence, who cannot be named until "the date on which [he or she] is committed for trial or sentence".
Since a trial is no longer pending, a suppression on the MP's name automatically applies once again.
"If there's a need for a suppression order to protect victims, to protect witnesses, to protect the defendant even, the presiding judicial officer should be able to impose an order through the same process they do in any other case," he said.
Mr Rau says that shifts the balance too far the other way and would mean a mandatory suppression order would no longer apply to victims.
"He wants victims to have to stump up to court when they're victims, perhaps child victims of a sexual offence, and ask for a suppression order," he said.
"Those children should automatically get it, and if the media can persuade the court they shouldn't get it, or if you have a bizarre situation like we've got now, they should be lifted."