Indeed, the lease from Qantas Company to Jetstar could be done at a loss, which would therefore make Jetstar look like a more profitable arm of the business than it 'really' is - which an interpretative investor might think as something of a grower, or a great new development within the company.
Whatever done between each company, it all evens out in the consolidated group reporting. It's just a shame there isn't the full transparency some would feel they need.