Interesting.
The SMH article said that there were no injuries, but there was severe turbulence.
I would imagine that most airlines would ground an aircraft after a severe turbulence encounter; only releasing an aircraft back into service after the relevant engineering inspections.
So... encountering severe turbulence 45 minutes into a several hour flight the crew decided to return to Perth.
Without being there, and only having the SMH article to base my opinion on, I'd still say probably a good call. In any case, I'd be surprised if the crew acted outside their company guidelines in such a situation.
DIVOSH!