That policy that you have found does not exclude bookings that are originally in x class it says that you cannot rebook into x class.
That means if you have any sort of ticket you cannot be re accommodated in an award booking class
. If you already have an award booking class you can be moved to any revenue class as long as the lowest in that class
I wish the Qantas phone monkeys listened to what I say.
The keep insisting X can only be rebooked on X even after I cite their own policy.
Will escalate via dedicated email but not hopeful.