What's the rush to international ops?
From what I have read the impetus is coming from City of Karratha (COK).
COK spent large amounts of money upgrading their airport terminal.
Karratha's $35m airport terminal upgrade complete amid hopes for international flights to take off - ABC News (Australian Broadcasting Corporation)
They had Silkair lined up to start flights from Singapore from March this year. They changed their mind and pulled out.
https://thewest.com.au/news/pilbara-...-ng-b88579791z
Which left an opening for Jetgo. It is not clear which party opened the conversation and it does not really matter. The opportunity is there for an operator to have their risk minimised as COK plan to "underwrite" the operation to some degree. So that gives Jetgo a low risk opening into larger jet operations.