No, he was entitled to call himself “doctor” between 1988 and 1991. He earned that.
It gets more dubious after 1991 to claim the courtesy title. If you did it, you would only do so on occasion and you should feel a bit embarrassed doing so.
As the years go by and he’s not a medical practitioner any more, use of the title becomes more suspect.
“Doctor” is not a protected title in Australia, so anyone can use it.
However, if he’s holding himself out to be a medical practitioner 31 years after he ceased to be one - which I’ve seen him do - that’s dishonest.
By the way, he hasn’t followed any training pathway at all. Which is why he could not work as a medical practitioner now, except in a theoretical sense under close supervision as a junior doctor.