Forgive me for the intrusion, but this statement is rather obtuse. What do you base this assumption on? Failing to capture them is not evidence of a low priority.
He is in high mountains, and if he is not moving, he is not making tracks. He is a religious leader protected by an inner ring of zealots- This is a hard nut to crack.
I am quite certain that I could walk out my back door with 2 days head start into these Rocky Mountains where I could easily defy any attempt to find me by anyone, including the full resources of the United States Government- and I am within the US borders.
Imagine how much harder it would be in the primitive surroundings of Afghanistan.