It's still very dangerous if the high explosives go if in an uncoordinated way. And then you have kilograms of enriched radioactive material spread all over. Not as bad as a supercritical reaction, but enough to worry about.
Uranium isn't really that radioactive. U-235 has a half life on the order of 10^9 years. It is only when uranium is brought together into supercritical lumps that it becomes a problem from a radiation point of view. However, it is also a toxic heavy metal, like lead, and that is a problem. That hasn't stopped militaries firing lumps of it around warzones the world over.
