the flip side, i guess, is that if he goes full retard (and he seems to be consistently on the brink), it could put enough strain on this old anglo-saudi alliance of convenience to help break the bond in half. in the end, if what you want is to see the saudi state dismantled like iraq was (and are we not funding them for the same reasons we funded iraq?), letting it play out may be a better course of action than taking him out before it happens.
but, you'd probably save a lot of lives in the long run if you just got it over with and got rid of him now.