By the time you get Terror Star tech they aren't useful. You have to build them in your space, they only move three spaces a turn and it takes three or four turns from when it's in position to make a star blow up real good. Also, there were no promised asteroids after the nova. I see above that they also have a range of 4.5? I'm not sure what that means, but that might even make them less useful. These things are not tear-assing around the galaxy blowing stuff up.
As a precaution I added a couple of escorts. No AI civ attacked it, so I don't know how that would have gone down. They don't appear to have any inherent defense capability. You'd think the AI civs might be slightly afraid if they saw one of these things in their neighborhood.
As for the AI using them, I'd love to see it. I've always been way ahead in tech by that stage.