I think this scene showed something that might be important. These girls have been brainwashed into thinking that Jack is evil and Aku is the responsible of the beauties of the world.
I wonder if they will use this as a plot point in the future.

Intresting point someone made.
This is very simulator to how Jack was trained from a young age to be ready to stand against Aku.
Difference being is that Jack actually HAD a childhood to speak of (with some good memories of his family and home).
And the many many places he went to stop Aku trained him as a Student with care (and not as a weapon).
I also have a feeling these people are more worshiping Aku than actually being his loyal servents.
I say this because it feels odd for Aku to intrust humans the very thing he rules over to defect jack (created from child birth or not).
And it also seems very strange he still sends out Assassins of the like.