Complete bovine scat. U-238 is as common as tin or tungsten, and more or less as dangerous as either. The radiation it emits is alpha particles, which cannot penetrate clothing, skin or anything else thicker than a sheet of paper. M-1 tankers ride into battle surrounded by tons of U-238, and while some people connect that to "Gulf War Syndrome," the possibility of inflicting chronic fatigue syndrome on a handful of people ten years from now is hardly worth a suicide bomber's time.
"Specialised equipment and facilities would be needed to turn uranium 238 into a fissile device like the Hiroshima bomb..."
Oh, I get it—this is one of those fabled British understatements. Replace "specialed equipment and facilities" with "years of research and development, the scientific and intellectual resources of an entire university physics department and an assortment of processing equipment extremely bulky and difficult to hide." U-235, the uranium isotope that is actually capable of killing people and breaking things, is much harder to produce than even plutonium. Iraq can't do it, North Korea can't do it—why would anyone believe al-Qaeda can do it?