It is misleading to conflate the issues of supporting Israel and otherwise remaining engaged in the gulf. US support for Israel is mainly a result of the power of a small but focused interest group to dominate politics in the face of large but diffuse opposition. cf. Cuba...
Our involvement elsewhere in the gulf is a matter of economic realism. Your rosy scenarios about the threat of a constricted oil supply are not born out by the facts. Yes there is oil elsewhere, but because gulf oil is produced at essentially zero marginal cost, it will remain a substantial portion of the world supply for decades to come. The problem is that one blow to this region can take off-line a substantial portion of world supply, without warning, in one big chunk. That creates a supply shock that would wreak terrible economic havoc, which then would leave a trail of human misery and death. If the US were to wean itself off of oil altogether, we would still be vulnerable because such a shock would shatter the economies of major trading partners.
So the immutable fact of the matter is that we face grave dangers from anyone with a match to the Gulf's powderkeg. For at least the next thirty+ years. Any solution that doesn't address this is a fairy tale.
