Taliban fighters are not soldiers. They are guerillas..
The whole guerillas v. soldiers thing is a distinction without a difference in terms of honoring the war dead. Should the fallen soldiers of the Continental Army in the American Revolution be honored any less simply because they were not in the service of an internationally-recognized nation-state at the time? Or the Yugoslav Partisans? Should Vietnam stop remembering members of the NLF guerillas who died in the war effort and only recognize the fallen NVA regulars?
If anything, there's an argument to be made that guerillas are owed more honor because they weren't simply conscripts fighting for morally-unclear objectives, ordered by their national government, but they instead volunteered for an ideologically-clear cause, in spite of the powers-that-be.
In this case I think it is completely acceptable to decide who to honor and who not to based on a moral or ideological basis. For instance, although on "Memorial Day" it is common practice to honor, along with US soldiers killed in all other conflicts, both the Union and Confederate dead from the US Civil War, I spit on the memory of the Confederate rebels-- fuck them. Nor will I respect "Peace Officers Memorial Day" until our government stops using the police as agents of mass repression. And the Taliban-- not that I'd expect to run across one of their graves ever, but if I did, I'd piss on it.
So, if we are not morally obligated to honor every soldier/guerilla/rebel, dependent on what they were fighting for, there is a strong argument to be made that for people who are not of a nationalist bent, there is no reason to honor the fallen soldiers of their own countries who volunteered to fight in unjust wars (though the vast majority that have been killed in Britain's wars were conscripts, and I consider it pretty damn disrespectful to refuse to honor your countrymen who died in an unjust war if they had no choice but to participate-- then again I may not be a nationalist, but I do feel some specific loyalty to my countrymen).
But I don't look at it like that. The way I see it is that even though I did not choose to be born here and even though, if I had it my way, we'd have a non-imperialist foreign policy, I do live in the heart of the American Empire and enjoy the benefits of that status, so I will respect the memory of my country's war dead no matter whether they are volunteers or conscripts, no matter whether they died in a just war like WWII or an unjust war like the Vietnam War. That and the fact that my great-grandpa served in combat in WWI, my grandpa in combat in WWII, my grandma in an auxillary role in WWII, and my ma in the US Army during peacetime, as well as my own very brief service with the US Army and my numerous friends who have served in the military-- I feel a personal moral obligation to give respect to members of the military which tempers my more internationalist and anti-imperialist beliefs.
HOWEVER, that's personal, and I wouldn't criticize someone for saying they don't feel like they need to honor the deaths of soldiers from their own country who volunteered to fight in unjust wars. Conscripts, as I said above, are a different story. I do, however, find the tendency of some Americans to want to get down on their knees and fellate every vet for fighting for their "freedom" a bit gag-inducing, as, since WWII (and maybe Korea) they have been fighting for no such thing even if they think they were.