Any form of forward planning requires assumptions to be made and plans are based on this and tweaked as necessary. In the past, computer modeling was reasonably accurate, schedules and fares could be set based on the previous year + or - a bit. Now it's a shot in the dark, no one knows how many people want to fly from Sydney to Hong Kong on the 23 of October and what price they will be willing to pay. The software that adjusts prices based on supply and demand needs altering, bookings could be lost if it sets fares too high based on a last minute rush and people decide not to travel, but revenue gets lost if it fills the aircraft up early with cheap fares in response to low demand as people wait and see.
QF need to start somewhere and getting a few flights going in July, possibly with similar fares to 2019 and adjusting from there seems a reasonable move.