I would have thought continuing on to Perth, being only 590nm away would have been a far better option. If passenger welfare was indeed the cause for landing in Learmonth here are some reasons why that does not make sense.
1. From the information we have, the casualties recieved broken bones, perhaps some compounded fractures and lacerations. If you present to a major hospital with these types of injuries over a weekend, you could expect to wait up to 3 days before a corrective procedure is carried out. The exception to this being any sort of head or spinal injury.
2. Head or spinal injuries.
These sorts of things can only be tackled by a major hospital with the latest equipment and techniques. Learmonth base to my knowledge does not have a specialised spinal unit. There is great risk in moving a spinal patient, I would have thought moving the patient once instead of the three hops involved in flying the patient (in a far less stable aircraft) to Perth would have made much better sense.
I think Qantas might have some explaining to do. Logically nothing adds up except technical failure prohibating the aircraft's passage to Perth.