If for some logical reason we cannot get everyone out in time because of logistics (would be an embarrassment). On top of that, we were not attacking, just removing people and we run out of time. Can you imagine the absolute shit show that would ensue if the Taliban attacked us/our troops for a good faith effort of removing citizens only and not even trying to get our equipment out? It would have to trigger a MASSIVE retaliation from the US. We know our military could absolutely WIPE them off the map. I have a feeling US is going to call their bluff.