[Protagoras]

Any rational person, trying to determine how easiest to get along with those around him,

You assume everyone is trying to get along with people in the easiest way. Bad assumption. Many are trying to figure out how to do whatever they want to other people.

Are they right or wrong?

Are irrational people right or wrong in doing whatever they want to do without regard to others?

[Junior]

Many are trying to figure out how to do whatever they want to other people.

Not many societies accept such individuals, do they? Nope. Societies attempt to remove, one way or another, those incapable of living peacefully with their neighbors. It's all part of rational self-interest.