It definitely sounds to me like a British actor trying to do some version of a southern accent. I thought that before I actually knew he was British, though I assumed he was British based on the way he sounded.
That said, it does have some semblance of a central NC accent that someone about that age would have, and it’s nice to hear a version of a southern accent that’s not one of the two stereotypical southern accents so often used in film (the upper class coastal southern accent where Rs are not pronounced or the backwoods southern accent where Rs are heavily enunciated).