By it's looks I'd agree it's most likely a hybrid, there's definitely significant razorback lineage there. Most likely it's a cross between one of the larger domestic breeds and a razorback. At my cousin's place several of his hogs have gone to between 600 and 750lb over the past dozen or so years, hybridization can produce bigger offspring than the parent strains so it's certainly possible.
Given the fervor over Hogzilla, they might be intentionally hybridizing on these game ranches to produce the real thing. On the other hand wild hogs aren't exactly rare in the rural parts of the South could have been natural hybridization too.
If I lived in that area I'd be glad it was dead, hogs are MEAN even domestic hogs. Given half a chance they will tear you up and they're smart. A hog that size is an absolute menace that's big enough fences aren't going to stop it unless it wants them to, it's big enough not to be afraid of anything and'll be happy to eat whatever it feels like. Hogs'll eat meat that one would eat a kid, eat a grown man for that matter under the right circumstances.
