As far as I know, that's incorrect. They dismembered him while alive and conscious. There was no throat slitting.
Well, that is very medieval then. But considering they still perform public beheadings, stoning, hand chopping, eye gorging and similar sentences routinely in the Kingdom, it’s not really all that surprising or out of character.
Funny how the human rights loving western governments didn’t have a problem with any of that, and their beef was SA is entirely to do with the killing of one of their assets.