Yes, but SIN-BNE-CNS or the even shorter (and infrequently served) SIN-DRW-CNS are far less than SIN-NRT-CNS. I'd call again if you actually cared to try to book. In theory if all flights were available you could do HKG-SIN-DRW-CNS-SYD-MEL-AKL-SYD-SIN, all on QF except the first flight, around 13260 miles. Shouldn't that be OK with AA?