No, what I think is there are many tools in your arsenal to deal with risk. If this particular aircraft entering your airspace has saturated it to the point where you can accept no more, than fair enough. Was that the case on this day? I doubt it. Australia slaps itself on the back incessantly about how good it is. I doubt that too. Australia thinks it is the world leading ANSP, that's bull****. There is serious cultural change that needs to take place in there.
No idea of the circumstances on the day. Have you considered the possibility that we work within the limited resources we have at our disposal?
I've a pretty fair idea how it works.
In the part of the world you inhabit. I'm not saying we're special or you're special but maybe, just maybe we make do with a system that's tailored for the level of traffic we usually deal with? We don't usually have a zillion aircraft so don't have the facilities to handle that many. Double the size of the sectors you have in the US and halve the number of controllers. Would that make any difference?
Was the aircraft offered transit at a lower level? Was the aircraft offered transit OCTA?
Transit OCTA? That's up to them - in class G they can fill their boots. I think the point was they were specifically wanting a clearance.