I totally agree with you Paul. Dependants of non-residents need to secure HK Immigration's approval before taking on employment.
However, my contention is that, even if you're not a "permanent" HK resident but only a HK resident, you may be able to sponsor a spouse to be a dependant. This is coming from your statement in the earlier thread (below).
Simplifying slightly... look at her HK ID card. If it has three stars to the left of the ID number then she is a permanent resident and can sponsor you as a dependent (subject to be able to prove that she can support you). If the *** is absent then she probably cannot.