How exactly would the U.S. conquer Afghanistan?
In that case, the rules of engagement hamper the foreign policy, which has declared no place for terrorism IIRC and that would necessarily include utterly destroying the Taliban and finally dealing with the ideology that spawned it.
Also, Obama’s sobriquet “War of Necessity” comes to mind. Not to mention, after Bin Laden was dealt with, travesties such as trading five Taliban terrorists for Bowe Bergdahl among other travesties too many to list.
When the author in the OP cites someone who counts Don Black among his friends as someone we must listen to, that destroys his credibility as much as Bill Kristol destroyed his own with his overt liberalism.