I have addressed many of the questions raised in this forum on my blog
http://constitutionalism.blogspot.com . Summarizing:
1. I have received several seemingly independent reports confirming the Farah article for several months from credible sources with connections to government. I conclude that this is part of a controlled release of information to various people, some of whom have written books on the subject, intended to inform the political class without alarming the public to the extent that it would cause economic collapse the the political repercussions of that.
2. My theory as to why the nukes already here have not been set off already is that they want to place more before setting off the first one, and feel that just a few will not be enough.
3. Their aim is nothing less than to compel us to all convert to Islam, in much the way people have done in the past, after losing battles to Muslims and being given the choice of convert or die. They want a world in which there are no more non-Muslims, ruled by a "Khilafah" or caliphate.
4. They don't care if we nuke all their cities. They consider cities sources of apostasy and corruption, even their own. They have a vision of a world of small farmers and herdsmen, with no cities or modern technology. Nuclear retaliation would be doing just what they want us to do. (That it could also kill all of them is something they don't grasp. These are not rational people.)
To understand the situation we are in, it takes getting into the heads of our enemies. This is not easy for most Westerners. To us it seems like madness, but it is a way of thinking that a lot of people have, people who can destroy us with modern technology. Just read their own websites.
I have followed these reports of Al Qaeda and the nukes for a few years now. They do take you to some really 'far-out' urls. I have always discounted most of the reports that tie into some conspiracy theory.
As of late, I followed up on one of these reports. What struck me with this particular one is the level of detail on seemingly inconsequential bits of information. That detail was not something that you would pick up on the internet. I personally know that those little facts are accurate. It added some verity to the source.
This could just be another yarn being spun with 1% fact and 99% imagination. It could even be deliberate dis-info. However, I watch the folks in the security business. A lot of folks seem awfully worried about something, and these are not folks at the political level.
In any case, for me, the latest report I found (not the one quoted here) added a stong piece of provenance to the idea of Al Qaeda and the nukes. I do think this should be taken seriously, but I certainly have not changed my lifestyle because of it.