he won't get scaled up because he's the only student - i think he made that up
as said above, whatever marks he gets in the hsc exam will be what he gets overall because his marks can't be scaled against other people. normally, you might get 60 in class assessments and be top of the class. then you do the hsc exam and your class mate gets the top mark in the hsc exam with 80. that means your class mark will be scaled to 80 and you'll get whatever you got in the hsc exam (pretend 70) as the other half of the mark.
total mark: (80 + 70) / 2 = 75. this is then scaled compared to the state. if you're in the top 1% of the state it will be scaled pretty high. similarly, if 75 is in the bottom 10% it'll be scaled low.
his marks. will just be scaled against the state.
so if he gets 50 in the hsc exams and compared to the state that's crap, his mark will still be scaled 'down' or unfavorably because he did crap compared to everyone else in the state.
for any corrections
http://www.boredofstudies.org/community/forumdisplay.php?f=134 post there and laz or someone more experienced will be able to help more