With organ donation the donor is dead and the interests of the still-living outweigh theirs.
I realize the OP is Australian, but here in the UK the NHS has done things like transfer data to Google without proper consent, and given that despicable firm's equally despicable data practices, that means control over the data is forever lost.
As for her contention that data can easily be "anonymized and securely aggregated", it is simply laughable, as all anonymization schemes this far have proven easy to defeat by a determined data scientist.
The way to get that data for important purposes like epidemiology is by earning trust through transparency and accountability, and shady practices like implied consent are the opposite of that.