Unfortynately Pakistan does not follow the Kutaliyian saying; 'Your neighbor is your natural enemy'.
In today's world where the possibility of conventional warfare and thus the likelyhood of an open conflict with between two easily distinguishable adversaries has diminished, only a dumbass country is going to follow the above mentioned course of forgein relations.
Seriously because with the advent of asymetric warfare, the ever evolving nature of LIC and the rat tag militia mastering the art of sub-conventional warfare, no country in its right mind would like to have an unstable state as its neighbor espacially if the residents of such a state are 'experts' in the art of asymetric/sub-conventional warfe, and thus the author's assertion that a stable Afg is an anathema to Pakistan is down right nasty , illfounded and full or mischief.
i mean, who the heck wants talibunnies to run amock in their neighbors espacially when they can move across a porous border to do thier deeds in your freely? i dont know, may be india is so fond of following Kutalia's teachings, why does it 'worries' about Pakistan going unstable (re-Pak nuclear weapons in wrong hands BS etc)?
So fuego sire, why dont you give one guud reason so as to why would Pakistan consider an unstable Afg in its benefit? But please spare me the usual indian rehtorics of Pakistan using their 'Pathan/Afghan Strategic Assets's against india/kashmir in any future conflicts?
P.S. Excuse my spells and formating, getting too old for mobile browsing.