ON the Admirals club web site, it states
" Access to over 40 Admiral Club locations worldwide and over 30 International lounged operated by oneworld partner Qantas", it does not mention about having to be on a QF fight.

In fact, at least here in LAX, which is a shared lounge, access is based on membership, not who you are flying. So, for example, I could fly into LAX on AA , and have a connecting flight on another carrier and still be able to enter the lounge based on membership and nothing else