What a load of crap! So why haven't the Chechens used them???
The thing about that, I think, is because the Chechens probably thought that had the thing gone off it would have given the Russians a go ahead to use tactical nukes on Chechnya. On top of that the device still had its impact even if it did not go off, since by telling the media where it was it meant that everyone knew. Thus they would be getting the psychological impact they wanted, and at the same time not giving the Russians an excuse to irradiate Chechnya.
Anyways, with that said the whole 'Al Queda's nukes' thing doesn't make sense. For one a radiological device is far different from nukes, and the article talks of Al Queda having a total of 68 suitcase nukes, a flurry of radioactive material, and 20 nuclear warheads. That seems more like a fantasy. Although I think there are some who would want bin Laden to have such weapons so that they could write about it.
I'd say this guy is trying to sell his book.