The second part of their journey which they had booked direct to SYD was replaced with a two-legger to Perth where they changed to a Qantas flight to SYD. Emirates told them that their baggage was checked all the way to SYD but it wasn't. The baggage was taken off at Perth and left in an unclaimed area.
When a diversion occurs then all the onward passenger's schedules will be thrown in to chaos. Once a plane has landed then the ground staff will take over and try and offer the best solution. In this case it looks like these poor people were offered the worst. Why they couldn't have been offered a night in DXB then then put on a direct flight to SYD is beyond comprehension. Those who dealt with this should be retrained in how to handle situations like this. (I can't believe this would be a cost cutting exercise in hotel expenses.) Did the passengers ever get reconciled with their baggage?
Oh btw the UK is about to be embraced in a week of snow and Sky are already reporting that around 250 flights are being cancelled, and it hasn't even started! Let the diversions begin!