There was an open discussion forum at the show where all speakers where available and the audience could ask questions. One question that was brought up was in regards to feeding live blackworms, and all speakers gave the same opinion (as mentioned previously). I can't offer info or speak for any of the panel members, but if I recall correctly the main concern was in regards to the worms ability to transport or cause various diseases.
Maybe some of the panel members will chime in.
HTHs.