Not to hang this crew as I don't know the circumstances, ( QLD PER can tricky this time of year balancing payloads etc and sometimes you don't have much wiggle room) but assuming that you can, who in their right mind arrives into Perth without substantial traffic holding or alternate fuel to go to Kalgoorlie, Geraldton, Busselton etc? Infact, not just Perth. The whole network is a shambles currently.
Also, why are delays in to Perth even a thing? ATC know we are all coming for hours beforehand. Why can't you begin to sequence us 800nm+ out? There isn't that much traffic. It's hardly the north Atlantic.