The bug is in the tooltip (back from many versions ago). I believe the behavior is as intended.
A major issue of the GalCiv3 team is that they don't bother updating tooltips or information text of any kind (including icons on the tech tree). I play a lot, and have just been ignoring the tooltips .. but that is not new-player friendly at all. If I were the team leader, I'd make sure that typos and outdated tooltips were fixed. But I'm not.