Why doesn't Savage Opress have Night-sister synergies as well as Sith?

In canon, Savage is raised on the same planet as the night-sisters. He was taken and transformed into the beast he is by the night-sisters (see CW mother Talzen). He was engineered by night-sisters to help Ventress get revenge on Dooku. Being that Sith synergy is already underwhelming, (especially since they are some of the most powerful beings in the SW universe and lack all the heroes and leader abilities like the Jedi in the game) can we give Savage some love and add a night-sister synergy to him since that is where he came from and the night-sisters were is origin. He is my favorite hero but extremely limited in use by synergy alone. Ashoka would be another good example to model Opress on (Jedi and night-sister synergy). (Bounty hunter synergy would be nice too but that's a discussion for another day)