What those Mastoi men failed to acknowledge is that they themselves destroyed whatever honor they might have had and they utterly dishonored their "caste" by this "revenge rape" of a vulnerable, defenseless, and innocent woman.
They could not have sunk lower.
Their "caste" could not have been more dishonored.
Obviously, the Mastoi caste is far lower than the Gujar caste.
The women in that tribe talked with the press many times. They have no doubts that their tribe is superior. The fact that she has been raped renders her entire tribe inferior. It wouldn't surprise me at all if her brother killed her to avenge their honor.
The issue is one of translation. "Honor" is the wrong word here. There is no English word to describe it, but "face" comes close. The clan felt that they had been "disrespected", or "dissed" in slum slang. And just like a slum gang, they cannot afford to let people think that they can be "dissed" without bad things happening to somebody.
These Pakistanis have no concept of "honor" in the Western sense