It isn't a choice for any IATA airline; the MSC rule (IATA regulation 302) is mandatory. So QF absolutely does honour it, however implementation is not yet automatic and most airlines have problems with staff not being overly familiar with it. I have inquired, and have it on good authority that showing the MSC rule upon check-in is guaranteed to work at QF. However, note that only the fare baggage allowance is covered by MSC, not any FF baggage priviliges (so WP would get the COS allowance even if QF is the MSC, similarly for BAEC status holders).