Because sport is so inferior to ATAR result we can even wade in and cancel basketball fixtures.
HOWEVER it is a total fallacy that your child will achieve better by being at a school which selects academically. Your child will be in the lower streams. Well done. On the other side of the coin, it is an easy way for the school to look good. But it is just the same mistake as Scots importing a couple of players. It will not help your child.
You're entitled to your view, but I'd make a couple of points.
School is actually about learning and exams and preparing boys for careers after school, in the school setting sport is secondary to this. Very few of these boys will be able to make a career from sport, most will have to get a real job like the rest of us.
Mostly students who are in an environment where high academic achievement is the norm will in fact go better. Students learn good study habits, have a positive attitude to the academic process and help each other achieve. The same is true of sport; import 10-12 elite rugby players and the other 3-5 in the team will improve and be carried with them as they are in an environment where everything is done at high intensity and achievement is an expectation. The same would be true for all sports.
For a school to "look good" academically, all the students need to perform well, it's not just taken on the few at the top, so I'd dispute your view that it's easy. In sport on the other hand, it is far easier for a school to "look good" as mostly publicity is only given to the first team of any sport. How many schools boast about winning the 14Hs or the 8th basketball?
The Headmasters have taken the only real action open to them. While the AAGPS Code of Practice sets out rules, it doesn't set out any mechanism for punishment. So if a school ignores the code and a quiet chat to the Head doesn't work then the 2 options are to either forget the whole thing and cop it or refuse to play the school which is infringing.
It's widely accepted that Newington imported most of a rugby team for their 150th anniversary and won in 2012 and 2013. No-one refused to play them so one assumes that there has been an amicable resolution to that situation. I can't recall any NC supporter on this thread denying the obvious.
From Scots we see that the school and it's supporters on this thread deny everything. We were consistently told by Scots supporters that it was all a plot to bring them down, no sporting bursaries and then their own "external review" at Scots found 61 "good sportsmen" on bursaries.
EDIT: If you go to the websites of the GPS schools you'll find that 7 out of 8 devote considerably more space to academic results than to sporting achievements. On the 8th school, you'll find that there is no mention of the 2013 HSC at all.