RV8builder
The ATSB report fails to mention any of the other factors involved in this (choke) incident.
These would be -
Workload
Internal intercom coordination
Other routine traffic handling
Weather
The coordination can be frustratingly slow. Probably the Traffic Manager and/or the Flow controller would be involved in approving the final clearance. They in turn may have had to assess the weather conditions down the line. If there were TS in the area, this would have complicated matters, especially VFR. If diversions had been going on closer in, the TM will be pretty conservative about having a VFR'y in the terminal area. If the pilot asked for IFR, then there may have been another round of coord. More time taken.
The BE20 mentioned in the report as not a factor, was still part of traffic picture, and I believe occupied some of the controllers traffic management strategies.
For some reason, maybe because it's an interim report, none of the above is made evident.
I am happy to stand corrected on any of the above.
CG