I haven't hunted in Karnes County in a decade, moved to DeWitt County, but I owned a ranch and hunted there for the 15 years prior. Honestly, that deer would not totally surprise me especially in the extreme western or eastern ends of the County. There are still some large ranches there that, well, keep their mouths shut about what they kill as that draws attention in Karnes County. I have seen a deer that was killed on a 5K+ low fenced ranch that scored over 200. On another occasion, the previous Game Warden came and got me from my hunting camp near Gillett late one season to show me a deer feeding in a field during a sleet storm, late in the season and late at night, that was definitely beyond 180. There is also a number of high fence places that have this kind of deer on them but they are store bought deer.
Karnes County has the potential but like anywhere else it boils down to large tracts of habitat, low livestock & deer densities so the habitat is not exploited, and low hunter pressure.