The linked post does not discuss Just War Theory at all. It discusses political positions of certain thought leaders as pertain to IHL. There's nothing wrong with that per se, except (a) if you're quoting Jonathan Parry more than Thomas Aquinas, what you're discussing isn't Just War Theory, even if it is desperately trying to claim that philosophical heritage; and (b) it isn't a "theory" at all because, within a secular framework, there is neither a set of foundational premises accepted universally as truth nor any testability. Just War Theory is only a "theory" within a Catholic epistemological framework. If your epistemological framework does not include a deity or the possibility of one day conversing with that deity, then it's meaningless to talk about your interpretation of their rules as being true or false.