It does seem silly to me. There is clearly a link to the Hamburg area, where almost all the people who were infected spent some time during the past week or two, and the others seem to have had contact with people who were there. I doubt that something infected got imported, I think probably the contamination happened there. The question is, is that place still contaminated or are the current cases secondary infections? But for any country to stop importing vegetables which do not go via Hamburg seems a bit excessive. You'd be better off not letting anyone from Hamburg in.