I don't think you misunderstood what I said, but you extrapolate to debatable conclusions.
My suspicion is that the Saudi upper-crust is thoroughly compromised with al-qaida symps and explicit supporters, and the regime is unable and/or unwilling to root them out. So the regime is complicit. This is a tricky problem for the U.S. to deal with, more so than, say, an Iraqi regime with zero U.S. support within it. That doesn't mean military action in Afgh is irrelevant. Military action against the al-qaida apparatus is appropriate wherever they are, including the Taliban regime.
If the hands and feet of al-qaida are cut off with u.s. military force, I expect that would deter any further generation of such activities from within S.A. Even if it does not, it's still the most obvious and useful thing to do, if it can be done.
Will the bombing accomplish this? Is it entirely focused on accomplishing this? I wouldn't know. What do I know about military strategy. I suspect that if you're going to attack somebody on the ground, it is helpful to blow them up for a while first, including their really big guns (sorry for technical jargon). So some kind of bombing makes military sense to me.
As in Serbia, there is the obvious possibility that other than Taliban/military facilities are deliberate targets. And there is the inevitability of missed targets and civilian casualties.
The unfortunate fact remains that there is no other agency to respond to 9/11 than the hugely imperfect U.S. Gov. Military action is dicey, but the legalistic and UN solutions seem much more so to me in the simplest practical terms. That they are politically impossible is beside the point. All of the options stink, much as we would prefer otherwise.
mbs