The only difference here is that the doll is less threatening than it's master. In fact, if you think about it, this is what role Seras essentially plays.
Blond hair? Check. Powerful? Check. Able to kill you with little effort? Check. Taken perhaps on a whim? Check. Significantly weaker than Alucard? Check.
All I know is if Shinku tries to slap this guy in the face...she's headed for a world of hurt.
