After years, I'm looking at this franchise again, and I'm playing around with GalCiv3+Crusade. I was looking at different victory conditions in the same game. I left "military victory" as the last option, for obvious reasons.
Given I tried other victory conditions in the same game, I had at one point all planets of the Slyne annexed to my faction (Terran Alliance). Their leader was still alive and happy (happier than before actually, as there was nothing to culture flip anymore). He still complained about stuff in his ZOC. I then bought his starbases for peanuts ( at this point, he valued 1 starbase at roughly the "Beam Weapon" tech), so he had no ZOC anymore. All that didn't really faze him, he just seemed to like Mr. Bradley a bit more.
Of course, there's still the Slyne fleet hanging around. It will be interesting to see whether I have to destroy his last colony ship, his transports or the whole fleet at this point. Anyway, I found that funny.