Since it’s a group so wonder if a group mental illness would make sense. I guess it could work for the court “look how out of touch with reality my client is, sith vegans, clearly they didn’t know what they were doing!”
It’s very easy to find apparent incoherences in humans behavior by selectively picking out and not searching the motivations. This is the base attack for teenagers bullying book.
Oh sure, and the jury. One can do both - mock murderers and their ridiculous ideology and study it seriously to, perhaps, prevent others from taking the same path. One doesn't preclude the other, though.
To a certain degree I think these group enjoy being taken seriously, being in the news, fawned over, their writings analyzed by people going over their "deep" and "insightful" ideas. So that direction could be playing into their hands to a certain extent. For now, I'll go the "ridicule" path, I think.