And its likely also going to be a case of "Computer says no" as most of the logic is no longer delegated to check-in staff but controlled by the rules programmed into the computer systems.
Which is perfectly reasonable and to be expected since QF's policy is no longer to transfer bags on separate itineraries ( other than for OW travel )
If there are agents which are ignoring the policy then that is providing an inconsistent service and leading to setting expectations which may not be met
If the passengers have luggage then I think that they may simply find that they are refused travel by Qantas due to lack of visa
I would suggest that they look at re-arranging their itinerary to not include Australia - or get a visa if it can be obtained in time