[Y]ou have this knack (almost six sense) of knowing how and why the regulator will react to almost any given situation …
Sorry to disappoint, but the reality is far more prosaic: the only skill required is that of being able to “read”.
The answer is in the regulations quoted and the AAT’s decisions, all of which material is available to anyone who wants to “read” it.
If some people are unable to read and comprehend the difference between the terms “decision” and a “show cause notice” – even the number of words is different – and unable to read and comprehend that any one or more of five grounds is a valid basis on which to support CASA’s and the AAT’s decision, that’s not my problem.