Thanks for the comment.
If I understand your argument correctly then you are not making a prognosis about future outcomes of legal proceedings, but you make a legal statement; more specifically, you argue that there is a specific rule in international law. This rule holds that international organizations that end up in some kind of judicial procedure should not be allowed to argue that their action has been necessary, if they have not sufficiently assessed “reasonable alternative means.” This argument is called “estoppel” (and also comes up in EU law in relation to the direct effect of directives). I would say that this is a “standard” doctrinal argument.
By contrast, what I meant by “prognosis of future outcomes” is somebody arguing that, if such court case actually takes place, then judges will decide in a certain way. This is something that cannot really be predicted with the means of the legal method.
→ does this make sense?