Then they would be consistent with many the leaders in civ who are cultural heroes. Honestly, the point of a leader in Civ is to be a figurehead for players to talk at and play politics against. Whether they ruled for 3 or 300 years is kind of irrelevant as long as they are accepted as a cultural icon. The Trung Sisters' main draw is quite obviously their status as a symbol of Vietnamese nationalism that has survived for 2000 years. I can't believe I'm defending them, because frankly I do find a lot of their support, particularly coming from the "civ with two leaders?" camp, to be kind of dumb. But Trung Trac alone would be totally fine as a leader, and in fact one of the last female leader options who wasn't just a female ruler, but one who became a sort of national personification.