Who knows what that animal's actual range was? 2500 acres is 3.902 square miles. Imagine a square area, almost 2 miles on a side. Plus, are the boundaries of that area fenced? Are they fenced tightly enough to keep this critter in? Who's to say it wasn't getting out through a downed part of the fence, and uprooting crops in some farmer's fields (feral hogs cause A LOT of damage to crops here, in OK, they're considered "Fair Game", and legal year-long). Here in OK, most "hunting preserves" are managed by the US Army Corp of Engineers, and are also usually associated with State Parks. I for one, would NOT want to be peacefully enjoying the wilderness, and suddenly have a massive brute like this charge me or my kids. I know that there's no reports of this animal doing any of this kind of behavior.
Personally, I think the young man's choice of firearm is a little lacking. I do agree with many of the folks here; that you want to drop your animal as quickly and cleanly as possible. The stress and strain of fleeing for it's life for 3 hours put so much adrenaline into the animal that the meat will be tough. If the animal were to die suddenly, with no warning, little to no adrenalin would be released into the blood, and the meat would be more tender (this is why cattle are stunned unconscious, then exsanguinated).
I don't hunt, but have no problem with people who hunt responsibly. Whether this young man and his friends were hunting responsibly, I'm not totally sure. At least they did track the animal down and finish it off.