Common sense should prevail here. To put it in simple terms, QF Group accountants would argue against the prioritisation of mainline recruitment to QF Group internal pilots due to the cost involved of replacing that internal pilot. Also QF mainline HR/FLT OPS would argue the fact that they would be limiting their target audience and potentially lose more suitably qualified applicants for the position.
Lastly, subsidiary airline FLT OPS would argue against prioritising towards internal applicants due to current shortage of crew. So the fairest, easiest and most economic way of mainline recruitment, would be, in my opinion, applications open to everyone, not discriminating because you are internal/external and overall, based on merit, which is what is stated on their website.