U.S. perspective Iran implacable enemy for discredit chaos forming Saudi Kingdom for praise

Iran sent them to Syria, Now Afghan Fighters are a Worry at Home is such a slanted headline that I had to read it several times and still can't understand the curve the argument takes from its beginning to end on this New York Times, our nations newspaper of record, article. The danger in Afghanistan are the Sunni terrorists not Iran's revolutionary guard. Iran clearly does not want chaos on their Eastern border so it actually supports Kabul, as the article is loathed to admit. But the writing on the wall indicates alternatives need to be considered because the Taliban despite their being despicable Sunnis are likely to prevail under their considered judgment.  As for the Revolutionary Guard, where are the local Shiites they could reinforce in Afghanistan such as in al Maliki's Iraq, al Assad's Alawite Syria or Hezbollah in Lebanon?  The point being that from official U.S. perspective Iran is an implacable enemy to be discredited and chaos forming Saudi Kingdom is to be praised both beyond reason, however, I don't recall any involvement by Iranians in the 9/11 terror attack on the twin towers.