SWH.
It would be transmission of business under FWA rules.
Especially a LH jet painted Qantas and based in AUS. The current FWA also now classifies transmission of business with associated entities. Hence why AIPA must agree to a S318 exemption to allow QF pilots to JQ on JQ conditions. Otherwise you take your agreement(determination) with you.
At the time Impulse became JQ it was not then flying QF routes but routes that QF didn't fly to. That was in the Workchoices era as well.
But the Fair Work Act changed all that post 2007. Designed to stop exactly what every company would like to do. Just start up company B doing exactly the same work but with inferior conditions.