this "tribunal" was offered as a legitimate and credible entity.
I don't see where the tribunal has been presented as anything it is not.
Therefore it is not at all fallacious to rebut that assertion that this "tribunal" is grossly biased, packed with anti-semites and truthers and not credible at all.
First of all, you must read carefully. Careless readers may be mislead when irrelevant facts are presented thinking they are relevant. That's probably one reason that people here get worked up. They assume that such posts- poorly reasoned and stuffed with irrelevant factoids -are only meant to mislead.
You came away with the impression that the tribunal was "packed with antisemites and truthers". However, that was
not claimed.
The post I replied to talked at great length about a website OP linked which also promotes truther ideas. However that website is in no way, shape or form connected with the tribunal.
It also mentioned former prime minister Mahathir Mohamad. However, Mohamed was not a member of the tribunal but only an organizer.
Mind that the people involved are all of high social standing. They are (former) high officials one kind or another. Those holding the tribunal were highly trained in law (AFAICT. I didn't check all).
They are by any standard people who must be taken seriously as a matter of social and political fact. If a similar group of people came together in the US (Ex-Presidents, VPs, Supreme judges, etc...) to raise awareness on some topic one would not simply dismiss that based on some kooky view that one or the other of them held. (I'm thinking there would be creationist among them and Hardcore Libertarians.)
ad hominem reasoning is not always fallacious, and that in some instances, questions of personal conduct, character, motives, etc., are legitimate and relevant to the issue.
It's really great that you know all this but we must ask if this is relevant here.
If someone asserts a fact which we cannot check then we are reduced to assessing that person's credibility.
Is this the case here?
The answer is no. Neither the law is secret nor the facts regarding the conduct of Bush & co. Special training may be necessary for some of the finer points but the big picture question should be open to anyone
We could debate their guilt with no recourse to the tribunal. Yet no one has even attempted to make a case against Bush's guilt. I can only assume that we have consensus on the issue.
That's why I don't see any particular reason to examine the reasoning of the tribunal or whether it's biased. Waste of time, IMHO.