That was the victim's immediate reaction and it sounds right. Swine have dominance hierarchies, they compete for mates and food. Those tusks are for intra-species use too, like antlers. This was a warthog being a warthog after being mistaken for a cuddly pet.
The simple fact is that a "corrective action" from a large animal can kill or maim a human, and the animal simply doesn't always have executive control over their behavior. Anyone who's dealt with a panicked horse knows that even when they don't mean to hurt you, they can reaaaaalllly hurt you. Expertise and familiarity go a long way, but the fact is that dealing with large mammals is inherently risky.
Territorial dispute? (I don't know much about warthogs)
Wild African animals belong in Africa, where, by the way, they evolved in an eat-or-be-eaten environment. This guy should’ve just gotten a puppy.