The problem with access to metadata is that CASA will have access to your Internet browsing history among other things and it then becomes a simple matter to run searches of its licence database against particular topics of interests.
For Avmed, what pilots have looked up the terms "heart attack", "heart disease", high blood pressure, etc. etc. etc.
For anyone facing prosecution by CASA, access to your metadata is going to identify your lawyers, your witnesses, your expert witnesses and your entire defence strategy.
As for associations like the RAA, SAAA, etc. CASa can get a very good idea of your business strategy and internal organisation.
There is really no limit to CASA power once they have this access and from available evidence of past experience, CASA is a vindictive, untrustworthy and corrupt organisation. They WILL misuse metadata!