ok lets break this down
- What makes you think he is normal, he could be something of a monster werewolf
- Maybe She-wolfs are too petite for him, thats why he looking for human sluts
I think you are probably right that he is unlikely to give multiple cells to one species.
But what species other than the werewolfs are there right now that might make good sex slaves? I doubt he will let us enslave the higher species, so no Elfs/Dwarfs/Humans/Giants. Maybe a sexy Zombie? or Ghouls?? always wanted to shag one of these?

I hope there are more like the batbreeder, I love the whole feral alien feel.