This idea is coming from more of a lore and flavor standpoint, but I think it would fit the Sower's theme of terraforming better if the affinity reduced your production on planets, and made it come from food instead. The conversion amount would probably need to be tweaked, as administrate heros would be even more power, and because of other possible reason's I can't do the math for, but I think this way, the gameplay better would reflect their theme of wanting to turn every planet habitable by making them more even more desirable.