Looks like too many customers decided they JUST MIGHT HAVE TO GO OVER TO THE AUSTRALIANS! So many that "the Australians" bought the team. This is poetic and this is why I'm glad blogs often stick around.
To connect the dots, it's overwhelmingly likely that Atlassian was in fact "the Australians" referred to and Atlassian's tremendous growth (which was foreshadowed in Joel's piece) is why they could by Trello 7 years later.
It's interesting to look at in JOS in retrospect because he literally blogged the birth of company A, its competition with company B and it's spin-off C, which B later bought.
https://www.joelonsoftware.com/2009/07/20/fruity-treats-cust...