This seems to be a difference between the base game and Crusade. In Crusade the Vigilant starbase with 50 HP is in the XML. While in Mercenaries files it is the one with 200 HP.
I see it now. I'd still like an official word on if this is intentional or an oversight. The Arcean tech\vigilant trait don't seem to have changed from base to crusade except for this. They also back ported many crusade changes to the base game, so if it was intentional then why not this? It doesn't strike me as an obvious change. They might have decided to remove the extra hitpoints, but why then leave the defense increase, especially when the great loss of attack power would make the small increase in defense irrelevant?