Hoss
What does the HSC prove? Maybe it could show that a potential candidate is able to study but so does an ATPL. If the HSC was that important it would be a regulatory issue, but it's not.
Hoss, with all due respect, things have changed. You might only be 9 years older than me (judging by your profile age) but I think you would be hard pressed to find many professional pilots in their twenties these days who didn't finish school. I don't know ANYONE who didn't finish high school - friends (including plenty from outside aviation), family, etc.
Given that a large majority of QFLink applicants would be aged in their mid-late twenties, I doubt many would have not finished school. I think you'll find it is the norm these days to stay at school right up to Year 12, even for a lot of those doing apprenticeships.
I guess what I'm trying to say is that I don't think it would rule out many applicants at all, but instead is just another tick in the box.