Here is a scenario, we know the Saudis arent the smartest people but they have $. We need a plan to fool them and take their $ and have them do our dirty work. It is easy, fool them to believe this is Shiite vs. Sunni issue, sell them planes and bombs, show them satellite photos to impress them, tell them this is a test of their manhood. You see this way they buy stuff from you and do your dirty work for you. I like this plan, I would do it, it is like tricking a kid, well we got these people with mentality of 12 year olds and lots of $ lets use them.
That strategy worked well until the late 1990s. After that the Saudi monarchs proved that they are more intelligent when compared to the American presidents. Right now, the scenario has completely reversed. The Saudis are just using the Americans, to achieve their own political and economic goals. This is very evident from the current situation in Syria, Libya, Yemen.etc.