Sunnis are 90% of the world's Muslims, even if you count Alawites as Muslim. A basic tenet of geopolitical strategy is to support the few (Alawites) against the many (Sunnis), the weak (Alawites) against the powerful (Sunnis) especially when land and resources are at stake.
I've never said anything about overthrowing the al Saud family. They are the only thing that stands between their troglodyte population and a terrorist-supporting Taliban state. The al Saud family are "moderate" in comparison to their population. I am saying that the al Saud family is doing stupid things in Syria that will boomerang on them, out of a misguided religious affinity with Syria's Sunni Arabs.
It's naive to think that the Saudis support the rebels out of a sense of religious piety. They do it because they are fighting their geopolitical rival Iran. They reason that they would much rather lure al-qaeda to Syria to fight against Assad instead of fighting them themselves in Arabia. Would you rather the islamists stay in Afghanistan to kill Americans than go to Syria to kill other muslims? I don't.