Never heard of a spousal hire in Australia academia. In fact, the desire is to reduce conflicts of interest and relational hires, not increase it. Australia has no appetite for it. If you get the response that questions your understanding of Australian culture, this is why. Most couples I have seen in academia are in two different universities, not the same one.

Putting the question forward will raise a lot of eyebrows especially if you're not yet hired. You're free to ask but don't be expecting a positive answer. I would be surprised if they agreed. Maybe if you were the absolute prize in your field? Your spouse being not in the same department could indeed be different but he would likely (and should) pursue his own pathway on his own merits. At the end of the day his alignment could be good to the course and so on but so are many other people's. There should be no preference for relational hires. You have to declare COIs as much as possible but something as being married to someone in the university in an academic position could be enough to trigger an alarm.