I'll ignore all the rubbish about sheltered workshops.
If so, with at least one scheduled inbound RPT aircraft from WA due to arrive shortly after opening, is there a contingency plan to ensure the tower is always staffed by a rated operator from the scheduled opening time? If not, why not?
How would such a contingency plan work? If AsA rosters 2 people to open the tower, people such as yourself jump up and down about public servants and wasting money, because 99.9% of the time they will both arrive on time and one of them will read the paper while the other works. Then if AsA only rosters one, and he sleeps in once in a blue moon, it's some sort of disaster? Why can't the contingency plan be that the QF plane lands using MBZ procedures?
One of the big clashes in ATC between commercial sense and safety, is staffing. If the wx is nice, the VFR traffic goes up, so if part of your tasking is low-level servicing (flight service), your workload increases. If you only deal with CTA, your workload will tend to be lower. If the wx is bad, FS is quieter, but high level sector workload goes thru the roof. How does one roster and have staff levels based on the weather? So when bean counters wander around looking at all the staff in the rec room, they have a fit. They never seem to be around when the thunderstorms are causing big diversions and the guys are working their arses off. Wx is only one variable- emergencies (try blocking a runway at a major airport and see how much work there is), one-off traffic peaks (airshows, easter {and before someone starts, although it is a known event, if your staffing is normally x, where do you get x+3 for half-a-dozen days a year} etc) and other things make staffing a hot potato.
Nothing is ever simple. Being a lawyer, you knew that, didn't you?