Well that's a semantics issue. Niven might argue that since the egg-producers don't gestate the young they're fulfilling a "male" role of merely producing gametes. But I'd argue that the female role is defined more by producing egg cells than by gestation: female fish produce eggs but don't gestate their young, and we still call them female. Therefore the "male" puppeteers that produce eggs are still truly "female".

The sentient ones are famously docile, cowardly and manipulative. I don't think calling them female would've been striking a great blow for progressive literature.