>So you'd argue that we should sentence people, and pass judgment on groups, without any legal basis?

Of course not. We should obviously have a trial before passing sentence on any individual, but it's ridiculous to suggest that legal judgements are the only valid way to establish facts about a particular situation. There were no trials relating to 9/11 because anyone who could have been sentenced is either dead or in another country. So suggesting that a trial be used as the burden of proof in this case is preposterous.