Those “white people” claimed ownership of other human beings. Stealing their slaves liberty, property, and labor from birth.
Killing a person who claims you as their slave is justifiable homicide. Killing the children is problematic, but the adult women were equally guilty. They are legitimate targets for a revolting slave.
Tactically and strategically, Turner and his followers made a mistake when they killed the women, as it motivated the enemy. But there is no moral issue with killing an adult who has enslaved you.
Was it the woman and the child he killed who enslaved him?