The plot thickens. The long awaited JNB-GRU flight has been loaded into the GDS for flights stating in October. I tried this routing

JNB-GRU-DFW-NRT-HKG-JNB (the JJ flight was available and selected).

Naturally, I got an error 300: Due to traffic restrictions on this flight you must be booked on the operating carrier. Change this segment accordingly.

Looks like a problem similar to QR. i.e. you can't use the online booking site for a flight that starts with JJ. Thoughts?