Just guessing, but I cannot see Virgin or CASA allowing RAAF guys to fly RPT ops without appropriate licences. I am guessing also, but I would think that the new 737 and Canadair Challenger pilots have been flying the Falcon 900 for a while, it is not as if they have just come from flying cessnas around Bankstown... Anyway, I am sure that what is being done is both legal and safe.
For info, many years ago RAAF flew learjets out of Amberly for survey. The RAAF crews required a civil licence before they were allowed to fly it. Also, the Falcon 900 is leased, yet RAAF crews operating it do not require a civil licence.
I also recall (someone please correct me if wrong) that several years ago the RAAF wings course was modified to include most, if not all, the theory of a civil commercial licence. In any case I am sure that there is no shortage of Falcon 900 pilots who 'just happen' to have their ATPL