Hmmm... this does not seem to be an unusual situation to me.
Every organisation has (if they don't they should!) rules about who is authorised to release information from the organisation. Those rules apply to information gathered or developed by people in the organisation, and that is fair enough.
If some of the scientists working for the CSIRO do significant work outside the CSIRO, the CSIRO policy does not apply to that work. CSIRO information releases must be in accordance with the CSIRO's policy. This has nothing to do with free speech.
Now if the CSIRO is supposed to be apolitical, but is being influenced by the government of the day to be political... that's a different matter!
Al.