For sure, the HSC requirement should be removed in my opinion.
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.
I don't know when or why QantasLink made the HSC a requirement. I have a mate who was not able to apply to QantasLink due to it but thats alright he was snapped up by the competition and is now flying jets. There are many similar stories.