My two cents worth:
I don't know what ASADA have or do not have but, having worked for a Commonwealth Agency once, it is not uncommon to seek legal advice from either the CDPP or an appointed legal eagle such as a retired judge. This advice can take some considerable time to obtain depending on the size and content of the brief and the extent of the advice required.
These people tend to be overly cautious and will not put their name to any advice that can come back at a later date and bite them on the arse ie a failed prosecution. They rely on their 'good name and reputation' for further highly paid 'work'.
If there is a technicality or two in the club's favour, the advice will more than likely recommend against taking legal action or any action that has the possibility of any adverse effects on either the agency or the person/s supplying the legal advice. Conversely, there could be a technicality not in our favour and the door is ajar for further action. This is unlikely as Government Agencies are not known to be risk takers. It may also set a precedent for other sporting clubs and/or individuals to use as a basis for argument in future matters.
I believe that they do have 'something', but like me when I go fishing, I know there is something on the hook but what it is I have no idea other than it maybe a fish.