Let me pose a question. If Osama needed to have plans for Nagasaki-type bomb, why do we think that he acquired Russian suitcase nukes?????
There is a huge disconnect in logic here. My deduction: the suitcase nukes (being in the hands of Al Qaeda) is mere wild conjecture, based on very little evidence and a whole lot of supposition.
If there was ever a topic worth of wild conjecture and supposition it is whether or not Al Qaeda has nukes. My assumption is that they have been acquiring EVRERYTHING COULD GET THEIR HANDS ON. That is certainly what you are I would do given the motivation and resources.