It is absolutely correct that nuclear weapons (and, to a much lesser extent, chemical and biological ones) are a deterrent, even to the US. Those who favor global interventionism see this as an absolutely terrible thing. But it depends on your underlying assumptions. If you view the US as a "benevolent hegemon", then all other nations must be stopped from developing nuclear weapons. On the other hand, if you harbor the ideals of the Founders (that the US "should not go abroad looking for monsters to slay"), then this is a non-issue.
Especially under the Clinton administration, the interventionism of the US went into hyper-drive....Haiti, Bosnia, etc...culminating in the Kosovo war. The American elites, who have taken it upon themselves to intervene in every aspect of American life, are now moving outward to apply their brilliance to foreign policy (I call this "interventionism as the final stage of liberalism").
Seen from this angle, any potential defense against unwanted control from Washington (be it guns in the hands of Texan cultists or nuclear weapons in the hands of various unsavory dictators) is seen as an affront to the power of the Washington elite...an effront which must be removed.
I believe that this is the motive for the missle-defense system as well. At first, as a naive patriotic american who believes in the ideals of the founders, I thought that the missle defense system was a good idea. I believed that its rationale was to protect the US from some rogue dictator deciding to launch missles at America. With more thought, the real agenda dawned: the real reason why Washington wants missle defense is so that they (the DC elites) can continue to engage in global interventionism without having to worry about nuclear deterrence. Thus removing said this "affront" from the decision tree of the elites.
I agree with most of the analysis, and again draw a different - and much darker - conclusion.
First, I do not think the proliferation of WMD can be stopped. The genie is out of the bottle. It is therefore only a matter of time before any nation who wants to acquire WMD will do so.
Secondly, why should a nation want WMD? Two reasons: as threat, and as deterrent. The former we can't do much about; there will always be crazies who want to kill other people, steal their land &c. The latter reason for wanting WMD, however, is a different matter. Nations seek deterrents because they fear attack, especially by a bigger, stronger, and meaner adversary. I see no way of avoiding the conclusion, that the current US posture of "pre-emptive self defense" is the single biggest incentive to any other country to acquire WMD as fast as possible.
The worst case scenario, then, is not what is presented in the article. It is a US attack on Iraq that sets off a mad scramble by half the countries in the world to acquire WMD, just in case they get put on the infamous "axis of evil".
As to the second main point of the article, yes, it is too late. The US hegemony ceased to exist on 11 September last. It was based on the perception, not that the US could do whatever it pleased, but that it could do so without fear of the consequences. That perception was an illusion, and it has now been broken. There is as much fear of the US as ever, but it is no longer a helpless fear. Now we know how the Persians felt after the Battle of Marathon.
Meanwhile, the US continues to amass the means to project force abroad, while continuing to leave its own defenses in utter disarray and to host large cadres of its enemies within its very gates. It is hard indeed not to conclude, as you do, that the US power elite is willing to sacrifice unlimited numbers of our people rather than give up its mad reach for global supremacy.
What now? I don't know.