I am not sure what the point of the Lee had some slaves whipped thing is. Slavery was legal. A whipping post set out front was the universally recognized signpost of a slave jail (slave trader) establishment. It was not only legal to have slaves whipped, it was the norm. Punishment ledgers kept by overseers indicate that slaves were beaten about once every three years on average. The point was, of course, not necessarily punishment as it was a way to intimidate. So, if Lee had paid to have some slaves beaten, it would have been legal & in no way remarkable in the society he lived in.