The rules do allow a service fee to be charged
Local service fees may apply on rebooking, rerouting, reissue or refund.
If your change requires a re-issue (or I guess if QR decides it is going to re-issue whether it was needed or not), then QR is free to charge a service fee.
(IIRC Qantas charges a service fee for economy class RTW changes, but not for premium classes)
With regard to your routing issue, QR of course faces on-going problems due to its being barred from flying to the UAE (and other regional countries) - see this thread
Qatar Airways - UAE, KSA, Bahrain and Egypt withdraw licenses and close airspace.
In that thread, you can see that generally, QR re-routes its passengers to such destinations only within a few days of travel.
Have you considered re-routing yourself, and so paying the USD125 change fee, to get what you want?