Advertisements I'm sorry, but you're wrong. As someone mentioned in this thread somewhere, the first thing Baltar did when he came aboard Galactica was to remove the update. The virus was broadcast by the Cylon attack forces, but the software update itself was an update to the defence network (with a backdoor for the Cylons as introduced by Six). I'm guessing the reason the older fighters never got updated was because they were never intended to be flown into combat (they were museum pieces when they got put into service) If there was no update, there wouldn't be a reason for Six to get involved with Baltar, to get access to the defence software. And Baltar wouldn't be so afraid of people finding out that he helped the Cylons get access to the defence software.