There is nothing wrong with the job, per se, and yes, it would be a dream job for some people, but not for people on a temporary working visa, unless the school could show that it was unable to employ an Australian resident. People can move to a city, and hope to figure out how to stay, but unless someone sponsors you, into a job, and housing, in AU, you don't get to do that dream job. Maybe the school sponsored him, which means they paid his health care, and insurance, and tax, and so on, but the school would have to undergo a process whereby they show they exhausted every avenue of trying to get an AU resident to do the job and had to import labour.
https://immi.homeaffairs.gov.au/visas/working-in-australia This site will explain it more thoroughly, Thijjsen was not a Permanent, or Skilled Occupation, or Short Stay visa seeker.
HIs fondness for Sydney is useless, and also a bit off, really, since he murdered a young Sydney woman for the hell of it, they should consider if Sydney is fond of him, more to the point. More gracious , really, if they just scooped up the ashes and dispensed with them in the North Sea somewhere. Remove all traces from Sydney, so to speak.
'Perhaps there wasn't a way to get a long-term residency/working allowance but we don't know for sure, right? But if so, maybe it's one factor in his irrational narcissistic act.'
But we
do know, very well, for sure, how to get a long term residency, and how not to, It's all set out in the statutes. Even marriage to an Australian is not a guarantee, although it carries weight in an assessment, and/or being a father of an Australian child carries weight, but does not guarantee residency.
What is certain, is that, had he lived, and served his sentence , upon release he would have been instantly deported back to the Netherlands, no matter how old or decrepit he was at the time.