From what I'm reading the only argument BRS have is their claim that CWL is insolvent and not an on-going concern that doesn't require tax payer intervention.
So surely, as with any business that's requiring restructuring, CWL has a solid plan to return to profitability and what BRS is trying to do is blocking that path to growth and in turn profitability. It's as if CWL is choking and BRS is putting it's foot on their throat.
Did CWL decrease it's losses in the most recent financial releases?
In the judgment, the CAT said that there was an on-going finance facility which was used as part of the reasoning as to why WG judged the business to not fall under the "ailing or insolvent" categorisation. Looking at the accounts while the airport is still making a loss, there are two critical points to call out. 1) the airport's outgoings include the management and oversight of the Bro Tathan operation and 2) it is building up a cash reserve for future investment, a reserve that is ring fenced for now.
The CAT concluded that the issue of whether the airport was “ailing or insolvent” had been directly and adequately considered by the Welsh Government and its decision was judged "not irrational". WG were judged to have reached a rational conclusion based on the evidence it provided as to how it reached that conclusion.
This is the point that Bristol disagrees with as you say yet, as the CAT directed, posessing a difference of opinion is not grounds enough to challenge the rationality of the WG assessment.
Bristol is likely to argue (again) that the decision was not rational and will try to pull numbers from the public accounts to support its conclusion, as it did at the tribunal. It will also complain (again) that the UK subsidy laws adopted as a bloc post-Brexit are too lenient and are "bent" in favour of public bodies rather than the protection of commercial competition. However, (yet again!) the CAT has already addressed the point of rationality (as above) as well as the rules - i.e. WG can only apply the subsidy according to the rules and framework guidance in place and not with one eye on other parties just because they might not like the rules or the outcome.
The final argument will (again!!!) centre around the WG's assessment of the effect on the market. CAT dismissed this argument as it was proved the WG re-evaluated their market assessment following the CMA's Subsidy Advice report of late 2024 which was partly critical at the time. WG actually listened and tightened their assessment proir to the subsidy submission. Bristol's "expert witness" painted a more critical assessment (of course) than the WG provided but the CAT ultimately discredited this as opinion, bordering on a critical assessment of the process, rather than fact.
The gloves are off now. Bristol Airport are seeking to push the foot further on the windpipe (as you say) and it will have zero issue spending millions more getting the answer it wants. They maybe 2-0 down but they've not lost the game yet and the prolonged uncertainty they are creating will feel as if the game is level and slightly in their favour, despite the score.
The *******s know exactly what they are doing and are playing the system as victims, whereas they are trying to play the system to kill government backed competition to protect their market dominance.