QF seems to have changed the rules recently for LAX-JFK-LAX ticketing, requiring connection onto a QF service. This is a commercial decision by QF, no doubt due to the heavy loads they have been having so they can pick and choose. Prior to this it was possible to book QF 107/108 cabotaged on any international ticket (and have done so). I'm not aware of any US DOT finding that may have changed the interpretation of US law in this matter; it does seem to be just policy by QF to limit these scarce seats in order to maximize QF revenue.