Sorry I can't give you an answer on that one UndereathTheRadar, but welcome to the wonderful world of airline (especially QF) people management.
Couple of years ago a collegue of mine was sitting on the infamous Qantas hold file. After 12 months of uncertainty, they finally called him up. He had to jump through a few repeat hoops and with that sucessfuly completed, was litteraly days away from an offer. Then nothing! After some weeks a letter arrived stating that there were now a large number of applicants superior to his and he was now no longer competitive. Gone, done and dusted! No amount of phone calls or emails could get him any answers. Chr!st, he even had a mate in Check and Training! Some time later he was accepted by CX. Their gain was most certainly QF's (and Australia's) loss. This sort of behaviour is typical of the contempt that has been shown to pilots over the years.
The reason for not offering a garrentee of employment is just another way of QF management hedgeing their bets. Keep em' guessing and in their place. God help us if they (pilots) ever think that we really need them!
Having said that, unless a candidate of the traineeship fails the program, or shows some obvious undesireable traits, I am quite sure that QFLink would in fact employ them at the end. These days they need all the pilots they can get!