My interpretation (not that this is written down anywhere) is that you have QF WP, and you have OWE as well, and the two are not the same thing. OW status is for reciprocal benefits on other alliance airlines. When you're travelling on your "home" airline, OW status doesn't come into it because you already have the status with that airline. So OW rules don't apply.
Yep. This. OW status is used when not travelling on your "home" airline.
The "home" airline can treat their own members however they want.
One example is AA not allowing their PLT/EXP members into ACs except when on an international or transcon flight. AA PLT/EXPs can't argue using the OW rules because those rules don't apply.
In the instance of QF treating its own elites differently, one example is: QF WP can access the SYD F Lounge when on an EK flight (other OWE cannot) and their one guest has to be travelling on the same flight. In contrast, a OWE (ie non QF) can guest someone who is not travelling on the same flight, however that guest must be flying on OW metal and code. This also applies to QF/OW COS. QF F can guest someone on the same flight only, OW F (ie BA F, ex-SYD) can guest someone flying on another flight (must be OW metal and code).
Also in dom J lounges, QF WP can guest two people, OWE can guest one.
Even though it's not written down, it seems quite clear anyway....