I had more in mind the scene where Vir sees Morden’s head up on a pike, and Londo comes in celebrating, “We’ve done it! We’ve eliminated the Shadow presence on Centauri Prime, and now the Vorlons will leave us be.”
And then the sunlight goes dim, and they see the Vorlon planet-killer settling into orbit. “No,” Vir reminds him, “there’s one thing left that’s been touched by the Shadows.” And he points at Londo.
So Londo tells Vir to kill him, do it, and make sure the Vorlons know you’ve done it.
Of course, at that very opportune moment, the Battle of Coriana VI kicks into high gear, and the planet-killer has to leave. I doubt we’ll luck out with such a deus ex machina. When it comes time for the earth herself to shake off her infection, she won’t do well distinguishing between us. So we really want to sort this thing out amongst ourselves; none of us would like what would happen if Mother has to get involved.