I wouldn't hold my breath waiting for negotiations to start. Qantas will appeal this one all the way up to the Full Bench of the High Court if they have to, as this is their one shot to get out of the groundhanding business altogether. This decision doesn't appear to be a full victory for the TWU, so it is likely that Qantas will grourp and mount some better arguments about how dire the industry is and why the airline can justify outsourcing it, or at least find a way to get around the technicalities raised in this judgement. They will argue that it has wider ramifications on how a business can respond during an unprecedented crisis. Given the lockdowns continue to throw schedules and ops into a state of flux, it is helping to make the case for why it is better to pay a contractor than it is having lots of employees hanging around.
Yes, I wouldn't be crowing about this 'victory' if I were the TWU. Any judge in any court on the same day could have seen it differently. That's why there is an appeal process and as you say, it will enable Qantas to refine their argument and I don't expect this to go beyond the first appeal, I reckon it will be overturned on appeal.
Lots of people on here expressing their opinion and I'm sure they believe they're right but when they can't even get the name of the Act of Parliament right, it's the "Fair Work Act", the body that administers it is "Fair Work Australia", via the "Fair Work Commission" and this decision was made in Federal Circuit Court, not before the Fair Work Commission.