Al Qaeda/ISIS conflict is it really good for the U.S.?

We need to really understand what is going on here. Yes it is true the head of Al Qaeda called out the head of ISIS. What is interesting is what he called him out on, it sounds like it is the same story behind the divison of Shiite and Sunni but with a modern twist. Al-Baghdadi claims he is the (Caliphate) leader of all muslims and Ayman al-Zawahiri called him out on it saying "We don't recognize this Caliphate". Even though the two groups are in conflict over this, al-Zawahiri says, "Despite the big mistakes (of Islamic State), if I were in Iraq or Syria I would cooperate with them in killing the crusaders and secularists and Shi'ites even though I don't recognize the legitimacy of their state, because the matter is bigger than that," "We have endured a lot of harm from Abu Bakr al-Baghdadi and his brothers, and we preferred to respond with as little as possible, out of our concern to extinguish the fire of sedition," "But Abu Bakr al-Baghdadi and his brothers did not leave us a choice, for they have demanded that all the mujahideen reject their confirmed pledges of allegiance, and to pledge allegiance to them for what they claim of a caliphate," So this looks like a double edged sword situation while they are in disagreement over leadership of "all muslims" they remain in agreement over their hate for us.
http://www.foxnews.com/world/2015/09/11/al-qaeda-leader-blasts-isis-in-new-message-but-offers-to-work-together-against/