No one is asking for favouritism in the selection process or any of that. QF can obviously have choice of the best possible applicants and so they should.
What internals are asking for is to be respected for the years of service they have provided to the group over some outsider off the street. If Jetstar or Qlink etc can't release someone because they are not sufficiently crewed, (let's be honest, this is purely due to their incompetence, poor terms and conditions or both) and need to hold people back for years, that those crew who were good enough to pass the selection process are not unfairly punished.
For example, someone at Jetstar has spent years being taken advantage of and screwed by a horrible management that see you as nothing but a piece of garbage, that was good enough to pass the process is screwed once more whilst someone who has contributed nothing to Qantas is forever in front of them. It's not that hard to understand.