XDDD Your headcanon is prtty nifty. Fic's not going to go that way but now I'm almost sorry. XD (that movie title oh god. XDDDDD)

Having a human for a concupiscent partner would only be a pro in the continued survival game if/when the drones are no longer an issue. No matter how hateable Dave is and how good for Gamzee, I really don't think he can fill a bucket (or that the drones would let him XD) and "being culled at the end of the perigee when drone season comes around" is a more immediate concern than "being lonely and unfulfilled" or "eventually going mudercrazy".