That is necessary in case the player character isn't tough enough to take on three scumbags and isn't inclined towards suicide. Without the option to chicken out, the first such encounter for a low level character could be instant death. And even if you're not inclined to play a combat-oriented character, you may have to go through the jungle, whether for storyline purposes, for a sidequest, or because you picked a "stormy start" and have to go through some jungle to find your ship.
But perhaps the dialog could be extended so that if you do chicken out, they get to laugh in your face, and you get the chance to reconsider before slinking away in total humiliation...