That ref from Mali is from a region that is nearly 100% Muslim. Remember, it wasn't just the call that negated the goal, but also the yellow card he gave the American for a handball on what clearly showed to be a clean header. In addition, he missed several obvious calls against the US.
After all is said and done, this will undoubtedly be the most blatantly mishandled umpiring job of the entire tournament.
But as Leylas said, the US should actually be the bigger culprit because the goals they gave up had nothing to do with bad officiating in the first half. If they play like that from now on they will lose.