You make an invalid assumption that Islam is homogeneous. It is not.
You assume that the fundamentalism of the Iranian Mullahs is universal. It is not. The Mullah’s beliefs are not even universal in Iran.
You do not consider the politics that drive the Mideast. Those politics while strongly Islamic, have an economic flavor. Recall if you will that Bin laden was a cast off, a shunned personna that was not liked nor accepted by the population of his own strongly Islamic country Saudi Arabia. He was literally driven out.
The leadership is in the GCC. The wealth and strong economic potential is in the GCC. If you are Afghan, the GCC is a better and richer ally than Iran.
Iran is the enemy, blood enemy of the GCC and they have no qualms at all about squeezing Iran till it hurts.
That by the way is the point. The bases and points of operation in Afghanistan are a real threat that puts the defensive squeeze on the Iranian generals. We have at least one good mind in the Joint Chiefs that is putting on the squeeze.
In case you forgot, Bagram and Kabul were inoperable for 4 days because some Korans were burnt.
Do you realize that the basic infrastructure at the larger air bases are controlled by the locals, who yes, are deeply fundamental Islamists? Despite the “different” hegemony, the typical Afghan wants every westerner gone and would rally against Western aggression upon another Islamic country.
You sound like an ignorant State Department drone pouring over IR and wishing upon a star We are picking off their competition. Locals also play both sides against each other. Also, they know when the Taliban attacks because the train of thought on Bagram at least, is that when the locals don't show up for work, you better stay near a bunker because mortars are coming.