I think you're right, the Aussies are throwing some cash at the tournament as part growing football in the Pacific - which explains why you'd add an Aussie team to the mix, still doesnt make the exclusion of an existing professional team any fairer or clear.
https://www.footballaustralia.com.au/news/football-australia-and-oceania-football-confederation-strengthen-partnership-grow-pacific
https://www.oceaniafootball.com/oceania-football-confederation-and-football-australia-strengthen-partnership-to-grow-pacific-football/#:~:text=The%20partnership%20is%20designed%20to,to%20begin%20in%20January%202026.
Says FA supports the idea of an Aussie club being involved but no mention of funding. the comp.
https://www.footballaustralia.com.au/news/football-australia-and-oceania-football-confederation-strengthen-partnership-grow-pacific
https://www.oceaniafootball.com/oceania-football-confederation-and-football-australia-strengthen-partnership-to-grow-pacific-football/#:~:text=The%20partnership%20is%20designed%20to,to%20begin%20in%20January%202026.
Says FA supports the idea of an Aussie club being involved but no mention of funding. the comp.