Pigs are omnivores, but they like raw meat. They aren't really hunters, but they are opportunistic predators. The farmer could have had a heart attack or some other health problem, but he could also have been careless or too trusting, and allowed a pig to walk right up to him. Given the state of his remains, they may never know.
My dad kept a few pigs when I was growing up. My brother and I had the job of watering the pigs, and hosing them off in hot weather. We did the job with spray nozzles from outside the fence. Dad impressed on us quite graphically exactly why we were NEVER, EVER to go into the pen or stick any body part inside for ANY reason whatsoever. He had us watch when he fed them corn cobs, and they chewed them up as easily as a person would chew a cracker. He said, "They can do that to your leg or arm just as easy. They will, too. They'll walk right up to you, calm and quiet, and take a big hunk out of your leg." He spared us the description of what happens after that, but we were old enough to figure it out. Especially since we had already heard him talking about the stories he'd heard growing up...about murderers disposing of bodies by putting them in a pen full of pigs.
Hmmm...interesting concept.I have a brother-in-law that I'm not crazy about....
Only kidding!