The "travel may not be via point of origin" rule does exist for the Global Explorer, however it's been deleted for the Oneworld explorer - the latter of which the OP is trying to book. The only remotely similar restrictions are the limits of 1 departure/arrival for country of origin, or 1 intercontinental arrival/departure per continent (with certain exceptions). Further, you're allowed 2 stopovers in continent of origin and the standard 4 segments for SWP. There are no further restrictions on how these segments are used, apart from the transcon restrictions for SWP.

QF will basically accuse you of trying to exploit the fare rules and scam them for cheap domestic fares if trying to ticket such an itinerary via QF. It doesn't matter what the actual rules are - good luck trying to convince them to ticket the itinerary if they insist on enforcing a non existent rule.

Painless and (relatively) stress-free solution: AA ATW desk.