No, it's their regulatory mission. Risk is to be minimized, no matter how small. Therefore if the chance of listeriosis causing even one serious case (presumably someone immune suppressed) is a positive number - even a very very small positive number - they view that as sufficient reason to put the kibosh on imports. Balancing risks isn't their mandate - minimizing risks is. Sounds crazy to me, I'd much rather have a situation where grownups can make informed decisions about risks (as if we don't already just by walking out of the house in the morning) but in this legal environment we have today...

Similar issue with thalidomide. To my knowledge the only downside to thalidomide are to fetuses. Now, those downsides are severe and obviously there were some terrible things that happened to some babies back in the 60s. However, thalidomide does some great things too - I believe it's a good therapy for some AIDS related symptoms, etc., but the view is that if it's on the market, some pregnant woman might take it by accident, and that's too much risk to take. Even if it was only prescribed to men and post-menopausal women.