Coming back to add, because I'm still thinking about this, that Londo's subconscious putting G'Kar into Cartagia's place instead of his own, when he's clearly roleflipping their positions in the shock whip scenario, really is a fascinating window into his mental state, isn't it? He doesn't put G'Kar in the role that he actually had in that scenario, which was a bystander (admittedly a culpable bystander) being, in essence, forced at (metaphorical, but implied) gunpoint to watch. His conscience-G'Kar is right that he had a duty to speak out, and he's right to feel guilty. But he was also at least partly a victim of Cartagia's sadism in that situation himself - but that doesn't seem to be how he's mentally parsing it.