They will follow the money trail when it comes to opening new bases. Taxpayer handouts are quite common if one wants to base xx aircraft in a particular place.
Adelaide Government in conjunction with Tourism SA gave Tiger $3m to start a base there in the late 2000s. Adelaide is often handing out taxpayer cash to airlines so that base would seem likely.
Bonza had already stated that quite publicly too, ie they wanted the airports to come to them and put an offer on the table. That generally only goes so far, and the likes re Sydney/Brisbane/Perth don’t generally come to the table, as they know Bonza will need them and will come regardless (Remember Rex throwing a tantrum re BNE and high costs, well they caved in eventually). Melbourne and Dan Andrews have been throwing money around for years, no surprises there that a base appeared.
