I am no CST expert but I believe the licences from CSIRO and CSL...

I am no CST expert but I believe the licences from CSIRO and CSL you refer to, R'shan, are based on patents that have expired or are about to (this is the basic whole blood interferon-gamma release assay patent, not the Intube one which is a significant advance on the method, belongs to CST and lasts until 2023). I'm not sure how easy it is to sell those sort of licences, but possibly its not too difficult because lots of biotechs have them.
I believe that CSL was not interested in commercializing Quantiferon originally, so they might feel a bit foolish buying it back. Actually, they are not so much a diagnostic company as mostly they sell blood products used in therapy and transfusion medicine, plus vaccines. That said, their products are widely used in diagnostic labs because transfusion departments (ie blood grouping and cross matching) invariably accompany these labs. Therefore their sales and distribution channels might be appropriate for QFN.
I don't think the government would care about CST being bought o/s, as most Australian inventions in science have this fate.