The best chance for a low-status person getting an op-up on QF is if their specific allocated seat is needed to seat a group/family together and the Y cabin is full. Sometimes it is easier to move one person to make room for a group, and in such a situation the status of the person seems to play less of a roll than the location of the allocated seat. But its impossible to predict which seat location might help in this regard.
Never plan on getting an op-up on a QF flight. If you want an upgrade, best try for an ODU at the Qantas Club for domestic flights, or waitlist for an upgrade for international flights - and expect to pay with points or UCs.