The statement is typically vague, and doesn't provide much detail, but it does state the following:
A four-member panel of the Classification Review Board (the Review Board) has by majority decision determined that the computer game Mortal Kombat is classified RC (Refused Classification).
In the Review Board’s opinion, Mortal Kombat could not be accommodated within the MA15+ classification as the level of violence in the game has an impact which is higher than strong. As MA15+ is the highest classification category available to computer games under the Australian Classification Scheme, the Classification Review Board must refuse classification to Mortal Kombat.
Computer games classified RC cannot be sold, hired, advertised or demonstrated in Australia.
As mentioned before it's important to note that the Classification Board are simply operating within a set of guidelines they must abide with. If Mortal Kombat does not fall into the MA15+ category, then it must be refused classification.
You can read the entire release here.