An interesting analysis, but I'm a bit skeptical. First, the only "wolf" that has threatened Saudi Arabia seriously in the past thirty years or more is the same fellow they're ostensibly now trying to keep in power. Second, the Iraqi oil supply presents no more of a threat under a new regime than it does now once the embargo is lifted - Saddam is no friend of the Saudis, see point (1). And third, the greatest threat to the Saudis isn't in Iraq or in the United States either, it's right there at home should the Wahabbis decide to take sides in the coming internecine warfare within the royal family.
But if I'm wrong it's not all bad - setting al Qaeda up in the desert in Iraq strikes me as the Saudi contribution to a target-rich environment. We may end up thanking them, or what's left of them, for that little favor.
Your third point seems to contradict your first. Also the Saudi's know that the U.S. will not allow Saddam to topple them. As for your second point; the embargo will never be lifted while Saddam is in power because Saddam will never agree to the conditions the U.N.(U.S.) has set to lift them. Your third point, I think, is irrelevant in regards to their position on Saddam. Their better off with him in power than with a democracy in Iraq.