And a nice way for SQ to effectively get rid of Tiger Australia without "loss of face"
Not really. Remember SQ just upped its stake in Virgin Australia so maintains a beneficial interest.
Not sure why all the concern about seniority. The reports indicate the operations will be kept 'strictly separate' so no blurring of the boundaries or transfer of value (revenues or costs) between the entities - unlike the red white silver orange conglomerate. I foresee someone at Tiger wanting to transfer to Virgin would have to apply, win the job, and resign from their previous post. Seniority would be part of the salary structure negotiation at the time of application/offer of employment. Good luck with that!