The information look to be carefully selected to paint a very biased picture. It assume a certain amount of metal is between the scanner and the human being, and the air flight comparison is there to minimize the emotional response to risk.

Let assume that this van and flying two minutes at altitude gives around 0.00something risk to cancer and thus death. If someone shoot a gun into the air, do they expose innocent people to the same risk as this mobile X-Ray van? What about a factory that dumps mercury into the water supply, and then compare that to the average increase in heavy metal from eating a single banana?

Objective information is easily shaped to change public opinion, and I for one will be very careful when it is about unnecessary exposure to risk (and I can guarantee that the operators of the van uses protective gear against radiation).