There was at least one cluster of vCJD (in Queniborough) traced to a small traditional slaughter house that was providing to butcher shops, and that cross contamination was occurring because in a slaughter/butchering operation with only a few people it is much easier for the prions to be carried from the brain/spinal tissue to the expensive steaks. A consequence of this was that all small abattoirs in the United Kingdom went out of business.

So your theory has at least one strong counter example