It depends. If you noticed the label on the case, the I.D. of the contents was scratched off. I know plutonium throws off alpha particles. Those can be washed off your skin. There are problems when ingested. Beta ones also from various metals. Remember that Ukrainian politician that got poisoned?
The guy that picked up that case needs to be monitored in a hospital. If he made any food with dirty hands, he might need iodine and a blood transfusion.
There is no Pu in that case. Those are shipping labels (Probably a Radioactive Yellow III) and list only the major isotopes. Depleted Uranium decays by gamma and alpha.
Alpha particles (effectively a He nucleus) are stopped short by a short barrier of air, clothing, even dead skin, and are only a hazard if inhaled or ingested (Pay heed Smokers!!!) They are Very damaging to tissue. But the case sheilds the alpha. The gamma from the DU is not. The DU is used to shield the Ir-192 source.
It is ‘non-sensical’ to say that alpha particles can be washed off. They are stopped and by capturing electrons, turn to Helium. It is the Pu or Ur that can be washed off.
Iodine is only required if exposed to radioactive isotyopes of Iodine. The idea is to fill the Thyroid with ‘clean’ iodine so it will not absorb the radioactive type.
Blood transfusions are only required in severe exposures that compromise the blood producing parts of the long bones.
Remember, this device is used, and used Safely at many facilities in a year by trained personnel. The fact that it fell from a truck doesn’t make it malignant or 0evil. It is what it is. As long as the source stayed within the ‘camera’, all is well to people involved.