I wouldn't like to be a betting man...
Hudson, your friend is faced with 2 problems:
1. Not speaking for other airlines, but the one I work for goes quite deeply into researching the information provided on the application form. I hope he or she has result slips for ATPL before he/she gets to interview;
2. If your friend is successful and subsequently information comes to light which may have affected your friend's initial application, he/she might find a visit to Centrelink forthcoming.
Honest oversight is just that (we're only human), however outright and deliberate deception will deservedly attract some form of unpleasantness....