you're trying to make it a moral argument, I'm not. Slavery was more nuanced and depicting only brutality is a fantasy.
no shit they used corporal punishment. the more benevolent masters viewed their slaves, especially house slaves, as children. up until about 40 years ago corporal punishment was used in public schools to correct behavior. some parents still use it.
it isn't like depicting the many facets of slavery is a bad thing. some owners were shit, others weren't, that isn't an endorsement of slavery or justifying it morally it's just being accurate