Somehow I imagine that among Freespacers, rather than having a legal age of consent, they instead vote on whether a pairing is Hot or Not, and if they vote 'Not', then that ship isn't going to sail, even if it's totes adorbs. I'm sure that could theoretically prevent any relationships with a power imbalance occurring, which is more to the point, and more of a sore spot for Freespacers in particular.
That's a bit off-topic, though. More to the point, Freespacers aren't really adults until they're at least 5. That's the youngest one could be expected to be found on a plotship. Wt that age, they won't have completed their tertiary education yet, which could be pretty limiting to their role-playing opportunities.