That’s what happens when violent militiamen become the norm. Being Taliban is more like an ideology. But there is no single authority leading the Taliban. Every violent group makes decision of perpetrating violence based on its own understanding of situation.
Those two guys might have thought that they would be safe among Taliban since they were their godfathers. And it is probably that most of those Talibanic violent groups would have considered them one of their own. But since all groups are independent, so it took only ONE group to disagree.
This is why no one should be allowed to be able to commit any sort of violence in society, in order for society to develop and function in normalcy.