Generally the rhino isn't messed with because he's just a stud like that. He's bigger than any predators in his realm.
With his very poor eyesight, a quiet observer is fine. Predators have to stay downwind because the rhino has a keen sense of smell.
When the predators do come after him though, he will charge (much like an elephant) and use his long horn to inflict as much damage as possible upon whatever threatened him.
